2old2nobetter

i have been chasing a code in my computer for a while now.car is '90 gtus na all stock.i thought it was a code 2(crank angle sensor).i switched out a bunch of parts(CAS,ECU,) but car still ran like sh-- and the mil was on.i checked the codes again today and figured out that i was reading the flash codes wrong. what i thought was a code 2 was actually a code 20.(oil metering pump pressure sensor signal out of range).upon further investigation,the sensor is totally dead and when i looked at the bottom of the omp the sensor was actually cracked and pulled away from the back of the omp.i am in upstate ny. could water have gotten into the sensor and froze cracking it or is this a common failure of these sensors?is there a way to eliminate these parts and run premix?if so,how do you convince the ECU to allow the engine to run with full power and not in limp-in mode.i am looking for the easiest way to fix this as i don't race or beat this car.if replacing the stock omp with a good used one is the easiest way then thats what i want to do. thanks.