99 Cirrus Lxi Computer issues
 

I have a 99 cirrus Lxi, california low emissions, with the sentry key. I bought it from a friend who put a junkyard PCM in it to make it run. I ran, but the red light on the dash would come on after I would start the car. It ran for about a month, and then when i would start it it would die after about 3 seconds. It did this a few times then it wouldn't start at all. I am looking for another PCM for it, but i was told that I have to get a PCM and BCM from the same car to avoid this problem again.
Any helpful info?
thanks