i have a 90 f150 302 its idling poorly it normally idels at 7000 if i just touch the throtle a little bit say bring it up to 8000 quickly it idles back down but goes down to about 500 then bounces around from 5 to seven it does that for a minute then settles back down at 7000 i changed the idle air control motor with one of another of the same truck and it still did it . anyone know or have an idea of whats going on ? thnxs shawn

 

idles at 7000 rpm!!!

i do not think so, nor does it rev to 8000 rpm.

 

sorry one to many zeros

 

check for vacuum leaks

 

MAP sensor?
try unpluging it and see what happens.
Good Luck

 

ive checked for vacuum leaks couldnt find any. where is the map sensor?

 

on the firwall about the pasenger side windshield wiper, it has a little plug and a vacum line, ive heard not to unplug or plug stuff like that bake in while its running, so i would saystart it then unplug it and restart it again and see if theres any difference.

 

My friend's truck would started idling at 2000 RPM or so. That's what it sounded like anyway. It needed a new TPS.

 

tps is that the throttle posistion sensor?

 

if i disconect the pcv valve from the hose it is attached to it idles fine no bouncing but it sits at 1000 rpm .