The idle is programed to be at 700 with my PROM. Sometimes the idle won't go below 1000. It does this sometimes though which leads me to think the computer has bad info from a sensor somewhere. Any clues as to what this could be. The TPS checks out.

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'89 Formula 383 TPI

 

Maybe your CTS is flakey and making your ecm thinking the engine is "cold".

 

I replaced that about a year ago. I'll definetly check it out. Would a MAT sensor cause that. I have never replaced that and it has 168,000 on it.

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'89 Formula 383 TPI

 

No, it might make the engine run overly rich or poorly. The CTS is the sensor that affects the idle. But if you T-stat is stuck open, that would cause the CTS to give a low reading.

If you have an automatic, your TC wouldn't be locking up. That would be another sign of too cold of a temperature reading fromm the CTS.

Also, you may have either a dirty IAC or the IAC is going.

 

Your minimum idle speed may also nead to be adjusted.

 

Well, the mixture is right, the TC will lock up properly and the minimun idle is adjusted right. The car starts perfect too. Is there a way I can check the MAF burn-off relay? The problem seems to come and go but recently it was mostly been around.

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'89 Formula 383 TPI