I know its not an f150 but couldn't find a section for the expedition. Figured its the same motor so you all could help. I bought it for cheap with a bad miss fire not sure what cylinders just did a tune up. I forget but I think they were motorcraft spark plugs I put in. But after that it ran grate so I thought. It would be intermiten but would all of a sudden while accelerating get a boost of power. That would last untell its next shift point and would always happen around 2-2500 rpm. Kinda like VTEC in a honda. Or it gained 2 cylinders. And would also start stumbling while sitting at a stop light for two long with it in gear and break on only after its warm. Never happens when cold. I hooked up tourqe and saw when it does it its misfiring on 5-6-7-8 randomly. Its missing on cylinder 4 all the time now which I believe is a plug, wire, or water-antifreez in plug hole sorry for the long intro but hopefully someone can help me out here. Its my first triton I'm usually in the powerstroke world thanks again.

 

Also under all driving except when sitting in gear with foot on the break warm cylinders 5-6-7-8 fire normally. #4 is the only cylinder misfiring all the time.

 

does anybody have any idea as what could cause it to miss on the drivers side like that?