1995 4.0 that sat for 3 years, I had it running and got a cylinder 3 misfire code. I replaced #3 injector, which was bad, and cleaned the remaining injectors. After putting everything back together still had #3 misfire code so I replaced plugs, coil, and wires...still had code. Replaced maf, fuel reg, and just replaced sending unit. When it ran somewhat smoothly it had a stutter when going up hill/accelerating and now I can get it to start but I have to mess with the throttle and it barely idles. The truck will also rev but try to die unless I rev it to keep it running. The truck only had 86k miles when I got it...what else could be wrong? The only other thing I can think is it somehow got out of time or has a wiring issue? I'm open to any suggestions as I have no idea and am sick of throwing parts at it. Please give me any tips you might have.

 

Welcome to the forum

"sending unit"?
In the gas tank?

So you cleaned the sock and made sure fuel pump was OK?
And there is a new fuel filter in place?
That liquid in the gas tank would not be gasoline after 3 years, and would plug up just about everything it came in contact with

OK, so do this first
Take off the IAC Valve and plug its 2 wire connector in
Turn on the key
Look inside at the valve and unplug the 2 wire connector, you should see valve close, plug wires back in and you should see it open, it only moves 3/8" but DOES move
If not then its stuck, you can try cleaning it
Also test voltage on the wires, red is 12v key on the other should be ground
You can only replace this with a Motorcraft(ford) brand or Hitachi brand

IAC Valve is what the computer uses to set Idle RPMs, high when cold, and lower as engine warms up
DO NOT adjust the screw on the throttle linkage, that is NOT an idle screw, fuel injected engines can not use an idle screw they ALL use an air valve, like Fords IAC(idle air control) Valve


ECT(engine coolant temp) sensor, 5volt sensor, 2 wire connector
This tells computer what to set idle at and when to Choke the cold engine
If this is telling the computer the engine is already warmed up, then engine would be hard to start and run poorly until it actually warmed up

There is also an ECT sender on the engine, 12volt, 1 wire(in 1995), this is used only by the dash board temp gauge, so these two are not interchangeable

There is an odd firing order on the coil pack
3 4
2 6
1 5
front

The 5 6 4 side can get mixed up, follow each wire to its cylinder on drivers side, then do it again, lol

 

I checked the IAC valve and it is getting power but did not move when the key was turned. Cleaned it with carb cleaner and still does not move so I am going to replace this and hopefully this does the trick. I will update the thread when I change it out.

 

Update for this one. Finally resolved this issue and happened upon the solution by chance. After replacing o2's, maf, iac, plugs, wires, coil, #3 injector, pcv, and I'm sure I missed a couple of other items. After the PCV replacement my code moved from a P303 to a P0171 lean code and was still surging under load. After many more hours of trending data from my reader and racking my brain I decided to take off and clean the EGR has that was one of the last things I had to replace before I dove into the valve train components. When I went to remove the EGR tube it had a weird feel to it and sure enough once removed there was a hairline crack on the bottom of the tube. The crack explains why I was having surges under load because as the EGR would open it allowed some of the exhaust from the manifold to leak and is also why I was getting the lean code. I have since replaced the tube and driven over 200 miles with no issues. If you are having some of the same issues hopefully this will help you out and save some money versus just throwing parts at it.

 

Good work

Thanks for the update and the FIX

Yes, that would be an obscure problem, not easy to find