How do I find my misfire?

All misfires on the same bank of cylinders, so it is something common to all of them on that side, internal vacuum leak, exhaust restriction on that bank, early sign of a blown headgasket, weak ignition driver circuit.

If you have a code for cat below threshold,and 02 sensor bank 2 the cat is not getting hot enough to keep system fuel trim balanced,once this code is tripped fuel. Trim goes full lean. Causing random misfire. Ls 4.8-6.0 are notorious for intake gaskets those are where where I would start. I had one of these. Tossed reduced engine power tried everything to fix it. No luck junked it.

Finally got this one sorted. Back pressure on bank 1 at idle was 8 PSI at idle. Change cat converters and problem was solved.