95 LT1 Ran rough, misfired, and exhaust backfired. Replaced opti but it didn't start. Found out it can be installed wrong, even if it goes on easy. Re installed it. It now starts but misfires and stalls out, It will sometimes stay running on idle but it usually will die or will die as soon as i put it in gear. I can keep it running if i keep on the gas but it will misfire hard and run really rough and if really give it some gas it will backfire out exhaust. It has new wires, new plugs, new icm, new coil, new opti, new water pump, 40 psi fuel pressure, a small vacuum leak but I temporary repaired it (waiting for new silicon lines to come in). I am Lost as what it could be.