Just for quick introduction purposes, I’ve lurked the forms for quite a while now because I have found that if I search long enough using the correct key words, I will eventually find a solution to the current problem that I am having, however I finally stumbled onto something that I cannot find a solution to. Hence why this is my first post.

I do apologize upfront, this is going to be quite long-winded but I know in my experience you kind of have to have the whole story to see the entire picture.

Now, because my last truck decided that it was time that it needed an engine rebuild and forcefully told me so, I pulled the motor I started working on that rebuild. However, with the fact that I make a living with my truck, me being without one was completely unacceptable. Knowing how long the engine rebuild was going to take along with finding out that I also needed a new exhaust system and transmission work, I worked out a deal with a friend to pick up his 1998 F-150 Stepside 4.2L V6 and a 5 speed.

He did inform me that the truck had set for 3 years due to him being out of the country for 4 years and his father passing away a year after he left. So I was already aware of bad gas and the requirement of a new fuel pump and filter.

So I went over to drain the tank, clean it and put the new fuel pump and filter in, which is really easy Once you remove the 6 bolts and just lift the bed off. Anyways, once the new fuel pump and filter were in we put fuel in it and fired it up. It ran a little rough, but we figured it was smooth out after it ran for a bit, and it did. At that point, we took it from where it was being stored at to my place, about 25 miles. The whole way I was making mental notes of other things that needed to be address to. Things like the clutch need to be bled, the brakes needed to be bled, new plugs and wires would probably be a good idea, etc.

Once on the highway it started struggling to get up to speed. When it hit about 50 to 55 mile an hour it would no longer accelerate. When I would shift into 5th gear it would actually lose acceleration and start slowing down so I would shift back and forth to get it to maintain speed and that was with the accelerator almost on the floor.

Finally got it to my place, I figured it may have been a faulty fuel pump so I took it back out and did a warranty exchange for a new one. Upon installation and firing the truck up, the same problem still persisted.

Continue Diagnostics to the fuel system and eventually found three fuel injectors that were not firing. So those 3 injectors were replaced and the other three was thoroughly cleaned, inspected and tested. While I was at it, I replaced spark plugs and wires because upon inspection I found that they really, really needed it and I also replaced the plenum gasket. Luckily, I have the 98 with the aluminum upper and lower intake so I didn’t have to replace it with the green seal bolts.

After that, the truck ran great, went and had it inspected and registered, went back to work and everything was great. For about 1 week.

I got up last Saturday morning to go to work and on my way the truck was doing great until I got on the highway and then all of a sudden it kind of, for lack of better terms, coughed, the check engine light came on and it felt like it had a miss. When I got to where I was going I got my scanner out, a cheap one because due to being out of work for almost 3 weeks, I cannot afford a live data scanner right now, but it came up with a p0301 code. So I pulled the number one spark plug and it was orangish brown but looked fine. I went ahead and replace it anyways so I could get home.

It was running fine and then after about 2 miles when I was leaving a stoplight, I shift from 1st to 2nd and around 25 mile an hour, right before I shift into 3rd, it bog down and no matter what I did it would not go above 25 mile an hour. If I shifted into third it might get up to about 27 or 28 mile an hour. I did everything from shift into neutral and try to rev the motor to get the RPM’s up, which it would a little bit but it had a very obvious Miss to it and it didn’t sound like the RPMs were getting as high as they should be.

While I was doing this I pulled off into a parking lot, shut the truck down and broke out the code reader again. At that point I did not get any missed codes but I’ve got the p0171 lean bank 1 code.

After reading the codes and waiting about five minutes or so, I fired it up once again and it ran fine for about another 2 miles/5 minutes and then did it all over again. Every time it bog down and I had to pull off and shut it down for a few minutes, I check the codes and and it was still only showing the P0171 code.

I was finally able to limp it the rest of the way back to my place I started troubleshooting again. At that point I replaced all of the spark plugs with Motorcraft Platinum plugs Gapped to .054, Motorcraft spark plug wires and a new coil pack. Took it for a test run, and the problem still persisted.

I then broke out the multimeter and tested the mass airflow sensor and it came back reading that it was within spec, but for ****s and giggles I replaced it anyways, disconnect the negative battery terminal and reset the computer to no effect on the symptoms and performance. It continued as it was but this time it through a p0171, P0174 and p0305 codes.

I then went through, pulled the plenum off again, and made sure all of the EGR ports and runners were cleaned out and did not have any blockage. Put everything back together, still no change. I went back over my steps with everything a second time and check fuel pressure. Fuel pressure is within spec. Pulled the #5 spark plug, tested it and the wire and was working. So I swap the spark plug into the number 4 cylinder and swap the spark plug wire to the number 6 cylinder to see if it through another misfire code. To date, I haven’t gotten another misfire code.

Eventually with doing research I found out about pulling at the vacuum line off of the EGR valve, plugging vacuum line and leaving the nipple on the valve exposed as a way to test the EGR system. Once I did that, the truck was able to be driven distances without the missing, hesitation or the bog to shutdown.

That lasted about a day and a half, then the symptoms started up again. I did notice that as long as the EGR vacuum tube was disconnected and plugged that I can make it a little further but after a fairly short period of time, the motor sounded like it was starting to miss again and then eventually stall out.

That was Friday.

I have checked the coil pack, spark plugs, and spark plug wires along with fuel pressure and everything is working great and there isn’t any crossfiring that I can find. I have performed a smoke test and cannot seem to find anything leaking in the vacuum system, inspected all the vacuum lines, replaced the pcv valve and checked the elbows and lines coming off of it, checked all fuses, did a vacuum test on the egr which affected the idle a little bit and it held vacuum at 15hg while the motor was running.

Tomorrow my plan is to turn off the intake manifold Runner control and the EGR vacuum solenoid to test them and make sure they are functioning. I’m also going to check with AutoZone and or O’Reilly to see if they have and exhaust pressure gauge so I can test and see if the catalytic converter is getting clogged up to a point that it needs to be replaced.

Another observation I have made that might help with any kind of ideas is that when the motor sharks missing or stalls, I pop the hood and the intake manifold is warm, but cool enough to touch. The heater hoses and the radiator hoses are not and if I allow it to sit for 5 or 10 minutes everything gets pretty hot. This originally led me to think the possibly the motor was overheating but the dash gauge read normal. I have noticed that from a cold start in the morning when it’s running fine it’s less than a block before the temperature gauge is all the way up to operating temperature. I check the coolant system and the coolant system is full, but I’m going to go ahead and replace the thermostat just because it can’t hurt.

Again, I apologize this so long-winded but I wanted all the information available on the off chance that somebody else has run into this very situation. I find it hard to believe that I’m the only one. So if anyone has any ideas, seen this before, anyting, don’t hesitate to let me know. It's getting to the point where I'm looking like I'm going to need some professional help, but let's concentrate on figuring out what’s wrong with the truck first, lol!

Thanks in advance!