I have had this particular F150 for two years. Last year I noticed coolant in the oil and some performance issues so I put in a new head gasket. After putting the engine back together I ran into issues with the truck idling. This is similar to issues I was having before the new gasket. It was having some trouble running after the rebuild and so I had an experienced mechanic come and look at it when I was having initial trouble and he noticed the timing was off and timed in the engine. The engine was running fine and able to idle at that point. Other than an issue with cylinder 7 (cause by a loose rocker arm for the intake). He recommended I drain out the bad fuel and tighten that rocker arm down and everything should be golden. I drained the old fuel; replaced it with new fuel and tightened down that rocker arm.

The situation I am in right now is that the engine will start but struggles to run ( sounds very bogged down). It has a pretty rough idle, with some engine shaking. If I add accelerator then it will intermittently pick up or almost stall. The engine will run like this for perhaps two minutes before it stalls out. The one time I have had it running long enough to test much, when I hit the accelerator the engine would bog down and have no power at all. I have replaced the IACV, the TPS, EVR solenoid, fuel filter, fuel pump and distributer cap. I have done resistance tests on the EVR, and EVP systems and they passed. I have checked the fuel pressure regulator, the EGR valve and the fuel pressure at the rail and everything checks out. It has new spark plugs and wires, and MAF sensor.

I am totally stumped as to where to look next and don't want to throw any other parts at this thing until I have a clear lead. Has anyone ever had any issues like this? Or can someone point me in a direction to look?
THanks.

 

Have you done a compression test?

 

I have not done a compression test. I am an amateur and self taught in terms of mechanics. Can you explain your thinking behind the compression? What might be going on?