OP
now that you have provided more accurate codes, assuming they are right, just "google" them for GM OBD1 codes....and 411 like this comes up which may give you a better understanding on what may be wrong.
http://theimportkiller.com/forums/index.php?topic=420.0
or any other GM OBD1 source for info
A FSM (factory service manual) is very helpful if you are trying to diagnose or do the repair work yourself.....assuming you understand the procedures noted in a FSM
also a recently replaced part does not necessarily mean:
1. the new part is good
2. it was installed correctly
3. the wiring/connector "to the part" is be good

