Chevrolet Repair: 95 chevy Z71 loping / miss, chevy truck, o rings

Question
my 95 chevy truck is missing or loping under a load. If you sit idle and accelerate to about 1200rpm the truck will idle up and then drop to around 500rpm. If you turn the air on it gets worse. has new fuel filter and idle air control, has new o-rings in TBI. What else could be the problem?

Answer
Hi Mike, 2 things come to my mind. First the fuel pump, Does it have good pressure and output. Need to have 10-13 psi. The second thing is a plugged cat-con. This you can test by removing a O2 sensor or disconnecting the exhaust from the manifold and running the engine.

Hope this helps

Mark