1994 5.7 propane misfiring

I have recently failed 4 e-tests. I have replaced new parts as each test was done. New cap, rotor, plug wires, egr valve and solenoid, map sensor, catalytic converter, air filter, spark plugs, mixer cleaned, setup and new gaskets. It's still misfiring causing higher hydro carbons when at high idle, but normal at still idle. It also seems to lose oil pressure when warmed up causing stalling when in gear. Any ideas of what I should do or what it could be.

start w/a compression test. If the valves are the problem all the tune ups in the world just don't help

Mileage?
Sounds like you have some serious problems. Missfiring is the result of bad ignition, low or high fuel pressure or your comression. Check and see if you have stuck lifters, bad burnt valve or two, flat cam,haed gasket, and such. Which by the way might have resulted from low oil pressure. First how low is it? This generally wont cause stalling, so see if you have some electrical, sensor or fuel related problems besides the onec you listed. Give more info

High hc is caused by unburnt fuel, bad plug , dripping injector , need more info , engine , milage, how does it run while driving and anything else you can think of