I have a 96 blazer 4.3 vortec. I recently has a multi misfire code come on. as well as evap and o2 sensor. changed dist cap and button. now I have cylinder 1 misfire and still o2 sensor.so next things next, plugs and wires were done. right after doing plugs and wires, I developed a "knocking" sound. thought it was a rod, but the noise goes away when accelerating.asked a few people about their thoughts and they pretty much told me anything they could. from wrong gas to exhaust leak. need help before it gets too bad..

 

We're going to need those code numbers.