1992 5 liter E 150, the engine misses after it reaches operating temp. I have changed plugs,plug wires. new dist. cap & rotor, oxygen sensor, EGR valve, vacumm line. I took it to the local mechanic for a compression check, all cylinders were about 135 lbs except one it was 100 lbs. He checked all emission sensors said they were OK. This thing runs fine until it warms up and then misses badly at idle. Any ideas would be appreciated.

 

I had a 89 Mercury that would die once it warmed up. Turns out the ingition module had an intermittent short that would occur once it warmed up so it would die. Once it cooled down again, it worked fine. The mechanic knew that the 305 had that problem and he changed it right away.