Chevrolet: 94 firebird formula idle problem, throttle position sensor, firebird formula

Question
94 Firebird Formula LT1. Starts fine and runs smooth, however on a cold start it idles at about 800 rpm and after about 2 minutes, as the engine starts to warm,the idle increases to 1200 to 1300 rpm. Opposite of what it should do. No service engine light.Unable to find any vacuum leak. IAC new about a year ago. Been advised by mechanics that bad o2's would not cause the problem. Any suggestions.

Answer
Unplug the MAF and start the car. When the car gets warm, see if the car does the same thing. If it does then its mechanical and not a sensor. If it doesn't do it again then its a sensor issue. Do you have any performance mods?

Are you able to measure the throttle position sensor voltage at idle? The TPS might be shot or need adjusting.

If its not the TPS and the idle goes upto 1200 regardless of the MAF being plugged in or not, its the optispark distributor.