91 4.3 won't run hot.

I have a 91 astro 4.3 tbi. Starts and runs perfect. When up to temp cuts-out, hesitates and dies. I can keep it running by feathering the throttle constantly and putting it in neutral and revving the engine. If i stop and let engine completely cool off, runs perfect again. Until hot. Any help?.

I am having the exact same problem with my 1991 GMC Jimmy 4.3 TBI

I had the same problem with mine found a plugged cat. To test remove an upstream O2 sensor if it runs well when hot then the exhaust is restricted.