Have had a constant misfire in 6 cylinder, changed plugs, still got code, changed coil, still got code, changed injector, still got code. Had compression test, looked good. The only time it runs rough is the first 3 minutes of cold start, after that runs smooth, all the freeze frame data on my computer shows that the misfire only happens at start. Could it be dirty maf, dirty valve? Is it time to go to ford delership?

 

Ok, this is gonna sound weird, i had the same problem, the exact same problem except on #3, threw all kinds of money at it, turned out to be..... A bad cat converter, i couldnt beleive it till ford explained that theres always one cyl thats the weakest and well be the first to misfire. Until the cat compltely blocks!!! Oh and i saw the bad cat with my own 2 eyes! Good news is cats r garanted to 120 k kilometers in canada and in the u.s i think it 80k miles, hope it helps good luck