Bipolar Misfire on 1997 Vortec 5.0

[shaneroze]

Running into misfire hell on my 1997 C1500 with a 5.0. Truck sat up from running just fine when I last ran her in December, but started and let her warm up every day just fine. Nothing but Random Misfire. Changed rotor, cap, wires, and all new plugs. Distributor was changed last October. Recently put a new brake booster in but she's not having any vacuum problems from that, brakes just fine, no hissing anywhere throughout the motor. Couple weeks ago, coolant temperature sensor on the intake went out causing the truck to act out a bit, changed that, then Bank 1 Sensor 1 started throwing codes, changed that out, acted fine for a bit, and would now again start that random mis. Degutted the cat when I rebuilt the motor itself two years ago, but that never really hurt her. My only guess is Bank 2 Sensor 1 considering my STFT but, what you guys think?

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[shaneroze]

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[Schurkey]

What are the misfire COUNTS per cylinder? Will that scan tool show misfire codes for each cylinder? Maybe your misfire is not random at all.

What is your fuel pressure? Computer is adding fuel (rich-command) like crazy. Fuel filter or injectors plugged? Pump wiped-out? Regulator faulty?

Of course, misfire will make the O2 sensors crazy, so that by itself can cause rich-command. Verify the entire ignition system, verify cranking compression pressure of all eight cylinders.