XJRobert

My 88 4.0 will sometime idle real high 3k when started. other times its fine. just wondering if anyone else has run into this problem, and what is the fix.

Ender

Mine does the same thing, I've looked into it and most likely it's the Throttle Position Sensor, I'm going to pop a new one in since they are some what cheap. I'll let you know how it turns out...

XJRobert

thanks, i got it from my dad and he said its been doing it for years, i love to know if its a cheap fix, i dont like it to blast to 3k right from the start. and with it at high idle the breaks suck, no vacume to help them out.

realtreeaphd

i was thinking you can just get some throttle body cleaner and oil maybe the body is sticking

darknezz

Mine when I got it would SOMETIMES idle around 1500 ONLY after its all the way warmed up and only in park/neutral, in drive it was still sometimes high like 900-1000 too. I cleaned the whole throttle body and parts, seafoamed it, gave it a full tune up (Cause I always do that to a car I buy) and it went away.

I've let a friend drive it the last few months and I suspect he babies it. It started to do the high idle again, one day I took it and did some donuts and hard accels and it helped it alot. ^_^

I suspect the throttle body just needs cleaned up again or maybe flaky idle control valve or TPS

It might be something else for you if its going up to 3k though, mine goes over 2k only on a cold start up then mellows down to 800. Its after its warm when my idle is up but not as bad as you.

I know what you mean about the brakes though... Even while in drive stopped at 1000 it wants to pull from you.