rough idle and miss fire

[CMCG]

Not sure if you're having the same exact problem as me, but mine would run rough at start up for a couple of months (would smooth out after a little). Progressively got worse, so did a bunch of research and here's a link to the thread I started. The 4.0's are notorious for the lower manifold gasket leaking coolant into the combustion chamber:

http://therangerstation.com/forums/showthread.php?p=1063896#post1063896

 

[DTMBENZ]

Just had a similar issue and it progressively got to the point where the truck wouldn't accelerate so finally I looked up some tests for the coil pack. This website really made it simple for me:

http://easyautodiagnostics.com/ford_coil_pack/ford_coilpack_tests_2.php

Sure enough, I found that the number 2 coil was not firing but number 6 would intermittently. Needless to say I'll be hitting up the parts store for a coil pack today.

Good Luck buddy.