Ok question... I have a 94 cavalier with the 2.2 and its doing something odd before i rigged it to never get hot it would die out and not start when it got to temp now it only starts dieing out at anything below 3/4 tank of gas and backfires through intake and exhaust if i rev it in neutral or park so far my compression ranges from 150 to 175 it has a new fuel pump and filter, new timing set, new icm, new egr solenoid, new plugs and wires. But sense i rigged the fans on at key on and gutted the thermostat when it dies i can just crank it right back on and go and is throwing a few codes but i cant fully make sense of them all...27, 28, 44, 55, 66
Here is a list of the codes and causes that will throw them.
The 27 and 28 are likely the main problem. They would be faults in the PCM (aka ECM). And if that is the main problem, it may also be the reason of the other codes, though those may be false and only appeared due to the failing ECM. Anyway, I'd check the ECM first and see what happens.
But first and foremost, if you haven't cleared the codes, do that and then see if any or all of them appear again. You can clear the codes by disconnecting the negative battery cable for a few minutes. Reconnect the cable and start the engine and see if they come back.
I have the Service Manuals for the 1994 year. I'll be happy to try to relay information from it to you.
Check all of your grounds, especially the ECM grounds.
Have you tested the fuel pressure?