gm tbi ?

I just finished install of a GM crate motor"350" in my jeep cj7.I used a 1992 donor tbi unit and ecm with harness.The problem I have is intermitten real high idle(800-1000rpm)warm or cold.I'm gonna have to say its not a vacumm leak cause its doesnt happen all the time.Would an idle air control of 32 indicate high idle or no?that according to a "tech 1" GMs scan tool.The motor is all stock with headman headers.Any help would help out a ton, thanks  

i have an 1989 Astro van and it did the same thing so i just rebuilt the tbi Friday night and it stopped doing that.  it took me about 2hours to pull it off build it and put it back on and the kit only costs 36.99 at auto zone so it is probably worth it even if it doesn't cure the problem because the tbi will be brand new for cheap and it doesn't take much time.  

the idle air control motor controls the idle speed....  it screws into the back/side of the throttle body.,...(big nut with a 4 wire connector usually)   it is commanded by the computer...

there is a passage on the right hand side of the tbi unit near a bolt head that you can see the tip of the iac motor... almost a key hole shape...   using a plug to block this passage you can set the base idle speed.... usually 500 rpm sometimes slower... this blocks all bypass air.

with the engine warmed and idling the IAC counts should be between 20 and 50....this should give you the best cold and warm start...

when you accelerate the iac is commanded open to work as a dash pot when you close the throttle.... so the manifold vacuum does not go way high...

the iac motor can go bad.. it is a stepper motor...
the wiring can be defectitve to it...
the throttle position sensor may be bad or have bad wiring to it...

with a flashlight.. if you can get your head over the throttle body you can see the action of the end of the  iac in most cases..

and i know that you have... verify grounds...

and also check for worn throttle shaft bores...

that can be checked also... watch the throttle position  sensor voltage readings with the throttle closed... it should always come back to the same voltage reading... if it comes back to differnt readings... it will mess up the thinking of the ecm and make it think that you still have your foot on the gas.... the tps voltage should not drift either....

this is the best reason to own a scan tool.... looking at what the ecm is looking at....  

Thanks for the input,when I figure it out I'll get back to ya  

Ok i had the exact same problem and i found out that the iac plug was in upside down i know it sounds simple but since i changed it around the idle has come down actually it came down too far so check that out as well and see if that is problem and also check that gasket beneath the tbi unit it sometimes gets sucked in good luck