Originally Posted by GMC boogie
The most common cause would be a faulty Coolant Temp Sensor or connecter. It threads into the intake manifold, left side of the thermostat housing facing the front of the engine.
I disagree with the coolant sensor. My 1990 Camaro with tbi also had this same problem. Try changing out the Throttle Position Sensor (TPS) it is located on the drivers side of the throttle body. That did the trick for me.