I have a 98 F-150 extcab 4x4, 4.6L with 150,000 mile. Recently my truck began to stall out sometimes when I come to a stop or slow roll. My truck idles fine at about 600-700 rpm and still runs great. It just stalls sometimes. I have noticed that right before it stalls out the needle jumps up to about 1200 rpms then just dies. It doesnt seem to be a problem when I am running my a/c though. Any ideas? I dont have any check engine lights on and I havent checked to see it its throwing any codes either. Any help is appreciated

I recently cleaned my throttle body and egr valve, they had a bad carbon build up

 

It is most likely the IAC. Buy a new Motorcraft IAC ...NOT the cheap aftermarket one you get from the auto part store.

 

If the throttle body and egr were gunked up, then the IAC motor is prob gunked up. I would at least pull the IAC motor off to inspect, and prob just replace if it is gunked up.

My grand marquis did the same thing, and the IAC was pretty nasty. I went ahead and replaced it from ford for about $70, which I believe is the same price you would pay at autozone or advanced auto.

 

Did you find anything yet?

 

I cleaned the IAC yesterday and it seemed to fix the problem. Only time will tell if it will hold up.