I have read every thread I can find on this and I still can't fix this truck.

I have a check engine light. I have codes P0171, P0174, and P0301 (I think). It was a misfire on cylinder 1 code. The engine runs really bad all the time.

Step 1 was to make a smoker and hook it to the hose that hooks into the brakes. There an no vacuum leaks anywhere. We had 3 people crawling all over this engine looking.

Step 2 was to change the fuel filter and check fuel pressure. I get a constant 38 psi that stays even when the truck is turned off. It is also constant if revving the engine.

Step 3 was replacing the MAF sensor.

I still get the rough running and codes 0171 and 0174. I have a basic code reader. I also have an Elm327 usb to OBDII cable to hook to a laptop, but I don't know what free software to use or what to look for. I am out of ideas...

Any help is greatly appreciated.

 

You mention all the actions your took to solve the problem, but the question arises as to when did you addressed the 0301 (1 cyl.misfire) code? Did you check/test the plugs & plug wires, etc. before you took the other actions to correct your rough running truck?

A master mechanic we know said IGNORE 0171,0174. They cover a million things & "nothing". He said the Windstar 3.8 v6 minivan is IDENTIAL engineering to the 2001-2004 f150 v6 4.2. First, a poorly designed valve cover allows excessive oil to be sucked into the plastic intake manifold via the PCV valve.
Second, the intake plenum uses "isolator bolts" to hold it down to the intake manifold. These isolator bolts have a sleeve that is essentially designed to allow the bolts to retain tension (keeping the plenum stuck to the manifold) and to block off any debris or oil that would enter the intake manifold via the PCV system.
The original "black isolator bolts" that Ford put into Windstars/f150 were not oil resistant and actually would harden after constant exposure. So, the badly designed valve cover allows oil to be sucked into the PCV system, which then introduces oil into the intake plenum, where it settles on these isolator bolts and weakens the sleeves and reduces the bolt tension weakening the seal.

These black isolator bolts and intake plenum port gaskets have to be replaced. The total cost is less than $100 and the procedure doesn't require any special tools or even a 2nd person to help out. For those of us who are not experienced MASTER mechanics, Youtube has videos showing how to proceed. https://sites.google.com/site/fordf1...P0171P0174-Fix

My childhood friend, who is a master mechanic, replaced the gaskets, the black bolts, cleaned up everything required, & replaced the pcv valve in my 2002 xl f150 v6 4.2.

 

I had the 171 and 175 codes as well replace then isolator bolts and the light went away.

For the mis Fire you may need a new coil. Or a wire is bad or a plug is bad.

These v6 are very pick and only like motorcraft plugs. I found out the hard way. So may want to try changing the plugs (motorcraft only) from my experience

 

The 0301 code came up after we started checking everything for the other 2 codes. It cleared itself and hasn't shown again. We checked the plugs. They all look good. They are maybe 25000 miles old. Replaced plugs and wires at the same time. Looked under hood after dark and didn't see any sparks jumping around. It looks like the next step is intake gaskets and bolts. It does have a very small valve cover oil leak, so we will change that too while we have the intake off. It isn't enough to leak on the ground. It just makes it look dirty.

Thanks for the input. I will post back after the intake gasket change is done.

 

Its the isolator bolts, had both and 01 3.8 windstar and 01 4.2 f150, both did the same as yours. The coils were also common issue on both, only happens on wet or humid conditions.

 

Ok, I made a day of it yesterday. I removed the upper and lower plenums. Replaced all gaskets and bolts. Cleaned everything. Replaced pcv valve. Replaced plugs. #1 plug was black compared to all of the others. Cleaned ports and butterflies in the intake. I couldn't find the gel, so brake cleaner was used. Removed the Throttle Body and cleaned it too. All vacuum lines were soft and had no cracks. For some reason this truck does not have the typical vacuum elbow that is always melted.

Upon starting it was hard to start. I expected that since I used brake cleaner instead of the gel. Once started, it smoked really bad. Once that cleared up, it ran smooth. Good idle. Good power. I took it for a leisure drive. It ran really good. On the way back, I started up a steep hill and all went to crap. I wasn't sure it was going to make it up the hill. It seemed like it had a terrible miss to it while under load. It felt like a miss or a hesitation... I got back home and no check engine light. I checked for misfire codes and none were listed.

The only thing not changed so far is the coil and fuel injectors.