What is the deal with the pcm unit? If I am attempting to replace mine with a used one, what do I need to look for. Do the numbers printed on the side have to be an exact match? Or will any of them work as long as they came out of a vehicle with the same basic setup. Mine is a 94, 4cyl. 5 speed, so will any pcm from 91-95 with 4cyl. 5 speed work? Surely someone has come upon this problem before. Any insight into this problem will be most appreciated. It will also keep my wife from asking "how much more time are you going to waste on that piece of crap?" They just don't understand!