The car is a 1992 Z28 with a 350(L98)/Auto. Ive got a chip in the car to make it idle around 900-950, and all of a sudden the car stumbles and idles around 700-750 as of yesterday. The car isn't even drivable because it stalls either on startup or when put in gear.

Some back round on a prior situation:
The reason for the chip is because we were trying to fix a stalling problem when and only when the car was at operating temp. A couple weeks ago we started replacing parts to fix this problem, because it started becoming a nuisance. We replaced the IAC motor, Injectors, IAT sensor, Distributor cap and rotor. Hooked up a fuel pressure gauge and they seemed to be ok? We had the ignition module check and it passed. Also had the ignition coil tested and it was considered ok by the books; I was told the primary's were in range but the secondaries were barely in range. The last thing we replaced was the cap and rotor, and that really helped. The stalling when warm wasn't really a problem if you could get your foot of the brake and let the car roll a bit.

But now 4 or 5 days later when you go to start the car it idles really low and upon first start up you need to put your foot on the gas for a bit to keep it running. You cant even put it in gear without giving it some gas.

Please this car is a daily driver and I need to get it drivable as soon as possible.

Heres a thread I made about the car stalling when warm: https://www.thirdgen.org/forums/tpi/...-stalling.html


EDIT: I noticed that the cruise control was on, and theres some slack in the cruise control cable that clips onto the throttle body. Could that have anything to do with a low idle?

 

What is the TPS voltage (non-adjustable) with the throttle closed?

 

.59 volts

 

Well we got it fixed. We re-did the throttle minimum air position. That put the TPS voltage out of range so we set it back into spec. Started it up and the idle was back to normal. Just don't understand what went wrong overnight