Long story short, bought a truck with issues. One code was p1345. tried a tune up, no dice, GM tech buddy said timing is off,it always wanted to come up 27 deg off while using a genesis to look at the cam retard. The closer you get to the 0 deg mark, the more it backfired and tried to die. After probly 20 times in and out with the dist trying to hop a tooth this way or that, i sent it to the dealer. There response after spending 2 days doing the same thing i did, was some sort of mechanical failure inside the engine, they didnt know what for sure. SO, changed entire engine and with new timing set, crank sensor, different distributor, knock sensor, all the gaskets, timing cover yadda yadda. Code still there. I wanted to torch the truck. Everything under the hood is different than when i bought it with the exception of the harness and ecm. Has anyone ever heard or seen of a computor causing this? I really appreciate any help

 

did you ever fix this?
i was thinking the dist gear may be going..

 

No, it did not fix it. Everything in the truck was new or different, except the harness, but I checked it pin for pin at the ecm and then at various sensors. We even went as far as to cut the tach wire behind the cluster to eliminate any issues of backfeeding. It stumped me, and the techs at the Chevy dealership. I finally got fed up with it and sold the thing.