I have no idea what an "OL fault" is.
Because the tool won't report it, or because the computer has failed?
P0300 because the tool won't report the correct code, or is the misfire REALLY random? Crappy scan tools LIE about P0300. The real code might be P0301--P0308, but the cheap tools report P0300 instead of the true cylinder-specific code.
What are the misfire COUNTS for each individual cylinder?
I'm starting to suspect you have a faulty scan tool. Perhaps a faulty computer.
You'll need to trace the wire harness to those two sensors to see if this is a harness problem.
WHEN is the fuel pressure "55"? If it's during the prime cycle, you may need more than one prime cycle to get to max pressure, and that pressure better be higher than "55".
Of course, that assumes that your fuel pressure gauge is accurate.
That's gotta get fixed.
A faulty oil pressure switch--or the wire harness connected to it--could cause the engine to stall when you pull the fuel pump relay. However, a faulty oil pressure switch/harness is not going to kill the signal from two O2 sensors, and cause the scan tool to fail to report fuel trims.
Better. Still not there, yet.
HOW do you know it was "super rich"?
If this thing is burning oil, all bets are off. May be time for serious engine work.
I expect the pressure regulator has a vacuum port, but being sealed inside the intake manifold, there's nothing connected to that port--no hose. It's just open to the manifold vacuum inside the manifold.
The timing isn't off. Turning the distributor DOES NOT change the timing. The cam sensor signal is not aligned/synchronized with the crank sensor signal; and the rotor tip won't be positioned optimally in relation to the terminals on the distributor cap.