i unplugged the iac valve and the engine stalled. plugged it back in, started it up, and using a mechanics stethoscope, (i hope i spelled that right), i listened to see if the iac was make any type of abnormal noise. it sounded a little spiratic at first but then settled down and sounded smooth, like it was working properly. i dont know if its the iac or not, changing it could fix the problem or it wont. i've been wondering if the problem could be related to the transmission, because from what my dad has told me about the truck, ( i purchased it from him, and he purchased it from where he worked) the original trans was rebuilt, then junked, then the repalcement trans was rebuilt before it was installed, then it got rebuilt again, only they went with a cheaper mechanic, and my dad said that he didnt like the way it felt at all, but it ran, and he didnt have to pay for it. so thats where i'm at, don't know what to do. any suggestions are appreciated.