Hey, I am having problems with my 1995 gmc jimmy 4x4. When I start it up it idles around 1k and slowly goes down, then after I drive a few blocks it will idle at 1800-2k rpms. If I let off the gas it will coast going 40 km/h and if I stop and put it in park it will idle even higher. Also when i'm on the highway I can't hold 80 km/h my rpms will go up and down 500rpm at a time. I can go 60 but not 80, I just cleaned out my EGR valve to fix my rough idle and I have to drive in 4x4 because if its in 2wd I hear a loud noise from my front end. If you need any other information I can give it to you, thanks.

 

Clean out the iac unit on the throttle body,and the throttle body its self. The egr was my first idea on the problem as u could of been stuck open. did it start this high idle after u cleaned the egr?

 

The high idle and rpm jumping started before I cleaned out the erg valve, I cleaned the throttle body a while back and it still looks good but I will clean my iac to see if that helps it.

 

Just wondering if you found a fix/remember what it was haha. Having a similar issue with my 05 5 speed.

 

There are many possibilities. Start with looking for a vacuum leak with visual inspection or spraying. Then if you have a scanner look at fuel trims at idle and 2500 to further investigate a vacuum leak. Other possibilities are the IAC/wiring, throttle body, other sensor inputs, powers, grounds, etc. This post is 10 years old and his problem is likely not your problem but I will be glad to help you find it.


George