Anyone familiar with Code 42??

[TireSmoke420]

alright guys heres the whole story. original engine in my 87 ran awesome it would light the tires up whenever it pleased with no hesitation. i lent the truck to a friend and got it back with a cracked head. since then i have replaced the engine 2 times. first time was a remanufactured engine this time its a junkyard motor. sister was driving the truck when it lost compression on the #7 cylinder took the whole motar apart looking for a problem found nothing but that motor is in the past. i got the junkyard motor put in 3 days ago or so, and it keeps popping up code 42 the last motor the remanufactured on did this too. its what we think ultimatly screwed the last engine. code 42 is when the distributer cant comunicate with the computer and therefore it does not advance the timing. also it only kicks the check engine light on when going up a hill or when ya stand on the gas. now i have totally rebuilt the distributer...module and pickup coil. can any one this of anything else to check?