Hi guys. I can add a few suggestions. First, consider a plugged exhaust system, in particular, the catalytic converter. If it is restricted, you'll hear more of a hiss from the tail pipe instead of the normal "putt putt" sound. Idle will be very good but the engine will usually tend to run hot.
Also look at the EGR system. I don't know if this applies to your engine and year, but Ford has had a real common problem with the EGR tubes becoming plugged with carbon. The confusing part is that when the tube to one cylinder gets plugged, that cylinder runs fine because all it's getting is fuel and fresh air. 100 percent of the exhaust gas flow is split evenly among the remaining cylinders. Eventually all but one tube become completely plugged, so 100 percent of the EGR goes to the one remaining cylinder. There's not enough fresh air to support combustion, so the only cylinder with a clear EGR tube is the one that misfires.
EGR doesn't occur at idle so the symptoms won't be noticed there. At higher speeds a single-cylinder misfire is harder to feel, but the Engine Computer will still detect it, and it will obviously cause a loss of power.
Monday, January 5th, 2015 AT 6:11 PM