Help with a 'dying' (possibly) transmission

[OVERKILL]

Ford vehicles have a very high misfire threshold before they'll set a CEL. Often, you'll feel it and be bothered by it LONG before you'll ever get a CEL for it.

Example: We had a coil go out on the Expedition, it would ONLY misfire under load, so when you went to pass, climb a hill...etc. It would buck and chug, I can only imagine how bad it would be on a 4 or 6 cylinder given that this was on an 8.

It never set a code/triggered the CEL.

I took it up to Ford (had a buddy who worked there at the time) and we hooked up their scan tool and he brought up the Mode 6 data that showed several hundred misfires for the one cylinder and none/next to none for the rest. We replaced the coil for that one cylinder and the truck ran perfectly after that.

 

[MolaKule]

Try to determine if this engine has an early version of the VVT.

I don't know if this is your problem, but my 2003 PathFinder with a V6 had a potentially dirty VVT control valve and exhibited the exact same problem.