Idels high and cuts out - 1996 GMC Jimmy

combination of emissions controls and ignition control issues and mine which is a 91 does the same exact thing because the defrost controls cause the engine to rev up high then slow down.. I disconnected the ac compressor so it does not come on..mine has some vacuum issues that I have not corrected yet but as old and as many miles as is on it Im gonna leave it alone until the motor blows up ..it smokes now and has over 300,000 miles on it.. rebuilt twice..5 head gaskets..6 timing belts and even when its really cold outside, it will start up when all my neighbors' cars wont..funny as heck..

You have a failed IAC (Idle air control valve) its on the throttle body,

No.
When the computer senses the compressor is adding a load to the engine it bumps the idle up with the IAC valve.
There may be a low or high pressure switch on the compressor which cuts power to the clutch if the freon pressure is too high or too low.

Could be that the fuel pump is failing. Have a pressure test run on it to see if this is your problem. It just takes a few seconds and is done under the hood. hope this helps and good luck....Please rate this post....

check if all vacuum air OK . check the idel air Beside idel control .check the agr . or you have bad voltage regulator .

It doesn't have one it is integral to the fuel pump module inside the fuel tank.

Your describing a vacume leak or a mis adjusted throttle body. Does it ever idel down? What engine is in it Desiel? If it's gas the AIS motor might be sticking or is bad. Does it run and is the check engine light on? are all the fluilds correct level? coolant level low can make the coolant senser lie about the temperture of the motor to the ecm and it'll command a high idel. Once the idel motor goes as high as it can it might be shicking and you can remove it and wash it off with carb spray and while it's out with the wire connected turn the key on and off with it in your hand and spray it with cleaner till it moves smoothly. With it retracted install it and try again, any vacume leak will make it idel fast. The trans mission will shift hard if the vacume line to it is off and it's on the back of the intake manifold and it goes to a modulater on the side of the trans. it can be off there too.

sounds like the throttle position sensor, I think that is the one that makes it idel rough

Front condenser fan ( only for the a/c) not commin on which in turn lets the system get hot. Hot means high pressure i a/cc system, high pressure trips the high pressure cut off switch.

I suppose, you wouldnt know till you tried.