I have a 1992 Camaro RS 305 TBI Auto< with 86000 original miles. Car is all stock. my car has been running fine up untill i took a 200 mi drive in it last week it ran fine on the drive avrg. 21 mi a gallon, then the next day when i started it up the idle was jumping from 400-2000 rpm the jump up and down is very consistant but it goes away and runs like a champ after it warms up. so i replaced the IAC valve and the problem went away... for 12 hours. next day same story. but now when the cars rpm's all jumping and you hit the gas there is no response for about 5 sec then everything catches up to itself and the car revs fine once off the gas back to sporadic idle until warm. its been 3 days and for the first two the car had to sit for hours and cool completely off for the problem to exist now its only has to sit for maybe an hour and it will do that. also smells like it running rich. i have checked for vacuum leaks and shorts and have found none, i rely on this car as a DD so i need to fix it before it totaly craps out, ive found a few posts with similar probs but no solutions and i cant afford to play the part guessing game. i have a multimeter to test but not sure what test and on what setting besides the obvious things like alt and batt voltage. PLEASE HELP i am changing the 02 to see if that helps

 

Are you getting any check engine codes?

Replacing the IAC valve fixed it temporarily.. makes me wonder if there could be debris in the passages leading to the valve. Try cleaning out the associated plumbing as best you can.

TBI injectors - I've heard of using a timing light to watch the spray pattern on TBI, but I've never tried it.
On port injected cars, the Multec injectors sometimes get shorted between the electrical terminals. That problem can sometimes be temperature sensitive. But I don't know if this is common on TBI injectors, or what the proper resistance for TBI should be.

The coolant temperature sensor can be tested by measuring the resistance across it's terminals. The resistance varies as a function of the temperature. I don't have the chart, but somewhere should be a chart showing how many ohms for a given temperature. Measure that when it's cold and the approximate temperature is known.
Make sure the sensor you're checking is the one that talks to the ECM, not the gauge.
This doesn't really explain the erratic idle speed, so it's probably not it.

The O2 sensor isn't active when cold for a few minutes, so I'm in doubt that it could be causing this. But after the system goes into closed loop then the O2 sensor feedback should prevent a rich exhaust. If it's still rich after the O2 sensor comes online then it should trigger a check engine light. If it's staying rich and you're not getting a code, I would suspect the O2 might be bad.
If the O2 is very old then it's not a bad thing to replace regardless. They gradually become less accurate as they age which hurts fuel mileage.

 

I replaced the o2 last night what a chore. But then this morning same syptoms but i had a check engine light, just ran it and got code 44... Says its running leAn

 

Thank you for the response btw