95 z71 with all kinds of problems need help
 

ok so i when i got this truck it had a blown had gasket, no prob went and fixed it. took the heads to get worked, started running bad, found out that one of the heads was cracked. got new heads from the shop and head gasket set as a compliment. so i figured i was going to go ahead and freshen up the valve train with a new cam, etc.

here's the new stuff:
edlebrock 3702 cam
push rods
lifters
springs to match the cam
adjustable timing gear set

everything worked great until today

here's whats wrong:

-i was driving my truck around and the rpm's started jumping up and down, then smoothed out
-rear main blew out, so instead of cussing and throwing stuff at the truck to blow off steam i started removing the horribly wired trailer brake controller that doesn't work.
-took it out and went to crank the truck up to move it and when i parked it, it died.
-truck is giving a trouble code 42

i know the trailer brake has nothing to do with the prob as the wires were only tied into the brakelight switch. but weird coincidence.

any ideas on the problems i'm having?

I looked through like 8 pages of post trying to figure out what code 42 is the closest i got was a po420 which is bad Cat efficiency. and from what i have heard is kinda a hit and miss code however if your cat is extremely clogged i imagine it would cause some weird things but the unstable RPM's is what really throws me off i also am not very code savvy so i doubt im even in the right ball park with the catalytic converter. after it died when you parked it will it still start and run or no?

no i can't get it to crank. i've done some research on the code 42 "The EST signal was not received by ECM for 0.5 seconds when EST mode was enabled or when bypass mode was enabled."

so maybe ICM??

i got the truck to crank today, and it will idle great then the truck dies like i turn the key off, no crazy idle or anything.

I would think it would be a computer problem of some sort either ecm or icm.

i'll check on the ecm. i took the icm to autozone yesterday and it tested bad 3 out of 10 times. but a new one failed 4 out of 10. anyone know how to check the icm with a volt meter?