Put plugs, wires, and new coil and then it till runs great and I can drive it 30 mins maybe then it goes to running with a slight miss

 

My question was is there any common problem with the 4.2 motor I'm missing like eating crank and cam sensors. Something like that

 

Did you run your OBD port for codes? If not, that is the first thing when you have a misfire with 96 and up vehicles. The OBD computers read 99% of the problems out for you, so there is little guess work. Not everything will pop up, but most will. If you have a hard misfire, it will come up and show where it is. You probably have the infamous P0171 and P0174 codes set. But, without what your truck is reading, those are only a guess. Check the codes, and let's go from there.

 

Sorry forgot to put it in the question I'm getting 171 and 174 and miss fire on 2 and 4

 

Had the same codes. Ended up taking upper intake off and replacing the isolator bolts and plenum gasket. Also while it was apart cleaned out the egr ports. 4 of 6 were clogged shut. Put back together and no problems or CEL plus more peppy and much much better MPG. Was only gettig at best 10 mpg highway now I'm getting 24 mpg mixed driving. Not all that bad to do yourself. Just the back three bolts on upper I take are a PITA to get to. Other than that was easy. For me at least.

 

But before I put this new coil on it ran good then bad just jumping back and forth

 

Check your ECT, engine coolant temp sensor. If it is only missing after it warms up.
Keep us posted.

 

Now it full time runs bad unless rpms are high

 

Reread the post by OTG02 about the isolator bolts, this is a service bulletin from Ford. Not sure if the gypo auto parts have the new bolts with the green isolators. Go to Ford for the correct parts.

What is making you think #2 and #4 are missing? Is that determined by a code also?

The 4.2L engine had a bad rap sheet in its early years. Its actually a sound engine with minimal problems. I am sorry to see its not available anymore.

Incorrect oil is its short comings. It has to use the 5W20 or it will wipe out the valve train. By using the correct oil, I'm at 238,000 miles, not even a quart down at is 5000 mile oil change interval.

Get back to us with your progress.

 

I have no power what so ever i can pull the shift to lock first and step on it and I can't even chirp the tires. The truck has 263,183 on it and ran like a dream a month ago just started With the code of p0302 and p0304 which are misfires I'm bout to move injectors to see if my problem changes location. I am new to this motor I do own a 5.4 truck that I am a real big fan of. Just want this to run right and give the fuel milage of before