I have a head scratcher (for me, anyway). My '94 4.3 CPI starts when cold, runs rough until it starts to warm up, and stalls. I will not start until it cools off. If I try to use starting fluid, the motor cranks for a few turns and backfires. I also notice that my oil pressure gauge reads low, even though the crankcase oil is at the proper level. Would a faulty oil pressure sensor/sending unit cause this problem? Also note, I have just replaced the fuel injector spider unit, but that may not be relevant. Any thoughts or advice from the experts?