Have an 88 camaro V6 2.8 liters. Bogs down and makes a backfiring noise from fuel injection manifold. Car bogs down extremely when engine's cold, a little better as it warms up, but still bogs. Popping happens warm or cold, as well as reduced power. Am I looking at a sensor problem? TPS switch, O2 sensor, temp sensor, mass air flow sensor? I've had injection manifold removed and cleaned and recently replaced the radiator, muffler and cat converter. HELP!!!!