so i was thinking about everything that was being said, and i remembered, the little actuator looking thing on the throttle body that pushes on the linkage IS the IAC.

what you should do, is let the truck idle, and with the hood up and the air filter assembly off, watch that little actuator and see if it pops in and out normally. you should be able to hear a slight hiss when it does also. also watch over time, cuz sometimes they act up, and sometimes they dont. you could even take it off, and clean it up and reset the computer to see if that helps any.

hope that helps!

 

Thanks for all the input. I did the idle control thing and it runs fine now.

For future reference how is the computer reset? Do you just disconnect and reconnect it?

 

Disconnect the battery for a min or so. Or disconnect the computer for a min or so.

 

Hi I'm having some nerve racking troubles with my 91 3.9 d150
I have replaced almost all the sensors on the engine and it doesn't want to start unplugged map sensor it started then plugged it back in and it idled rough and when put into gear it would stall don't know what to do