I finished my swap a few weeks back of an '02 5.3 in my '94 obs. It was misfiring like crazy. Changed the plugs and wires. Still misfired. Check the coils with multimeter and all 8 were within specs. Turned out most of the injectors were clogged because the motor was sitting in a warehouse and the fuel lines were cut and not covered. I got 8 injectors from the u pull it junkyard. Clean them really well and all 8 cylinders are fire correctly. I did not have any codes though. But when checking the scanner and looking at bank 1 and 2 . Bank one showed that it dumping too much gas.