Heres's just what I'm talking about.
5.7L Engine Miss. Very Frustrated! Tried Everything. He had 144 hits and 2 repies. Your telling me that out of 144 people, not one single person knows a damn thing or has had a similer problem? Right. I'm sure he would like to thank you for looking.

 

try a compression test, it sound like a dead cylinder, if all the new parts are good that is. I have had new parts(especially spark plugs) that were no good.

does it do it all the time or is it intermittent? if its all the time try pulling the plug wires one at a time to locate the miss?

does it miss badly at WOT? or does it go away? if it goes away at WOT check your vacuum lines and there condition, hard, brittle lines need replaced.

is the exhaust in good shape?(had a doughnut gasket go out that sounded like a miss once.)

did you replace the pickup in the bottom of your distributor?(can't remember what its called now) they can cause misses when the get hot

I know most of this you gm tech buddy should have done already just trying to give you some ideas, good luck.

 

mabye 3 ppl looked at his post 144 times? id worry about getting an anser to your ? and leave the rest to us. if you have a problem ask and we will try to anser.