Try replacing you crank sensor, be careful they are not fun. Mine was doin it too. replaced it and all is good. Also what are your rpm's at? if they are at about 500 turn your defrost on. If the idle goes up to about 700, it is your IAC. Mine was doin that too. Hope this helps.

Also, there was someone on here who was talking about a bucking and not getting the rpm's up over 2800, and felt like it was being pulled back. I can't find that thread anymore. SO....If your reading this what you discribed is exactly the same as what i was going through. Change your crank sensor. Right hand side of the block. Very easy to get too but it's a b***h to get out. Be careful!!!!!!

Hope this will help anyone else, especially the 4.7L