high idle

[jmjlc]

I have a 1996 suburan 5.7 with 155k miles. When driving and slowing to stop the eng stays at a high idle or putting into gear the eng seems to go into high idle so much that I have to apply alot of brake to keep it under control.It seems to do it more when its cold than hot but does do it sometimes when hot.I have replaced the following.
1) replaced idle air control valve--and set plunger to correct length
2) cleaned egr valve
3) checked for vacum leaks
4) replaced fuel pump
5) replaced fuel filter
6) replaced cap,rotor,plugs

Any ideas???

[Fireplug]

you forgot the most important 1
the Idle air control valve on the throttle body.
Remove it clean it and the throttle body also.
Clean the M.A.F. Mass Air Flow also its on the air filter duct tube going to the throttle body

[jmjlc]

I did the Idle Air Control Valve. I have also cleaned everything.

Any more ideas??

[Fireplug]

Did you remove and clean the MAF sensor?
Also check for any vacuum leaks from the vac lines any hisss sounds from engine area.
check engine light on?

[Fireplug]

also check the coolant temp sensor it might be out of wack and making the pcm think that the engine is cool and incressing the cold idle

[jmjlc]

cleaned maf sensor and no vacum leaks and no check eng light. will look into temp sensor this week end. should i clean it or just replace it? where is it located??
thanks

[Hoyt]

I am new to these forums and just happened to see this post.

I had a good mechanic I know look over the 90 Suburban I just purchased and he was telling me some of the common problems he has seen over the years. One problem he mentioned sounded exactly like the one you described and he said is was often caused by the throttle body gasket leaking. He talked like it was not a big deal to change.

I just thought I would post this in case it may be of some help.