after all this time with no update.
i can only guess 2 things.
1. the problem is solved, it was something stupid and he does not want to tells us about it.
2. it's not fixed yet, he went nuts, and he was carried off in the white wagon with a full wrap around suit.

 

Same problem happened to me and it turned out to be stuck injectors that sat around to long.

 

we found a couple of hairline cracks in the roof & & valve seat of one of the heads. i am really dissipointed in GM. The cracks are not visible unless the valve is taken apart. replaced it with another head on the shelf late last night & ran fine. The puzzling thing we can't figure out is that it passed the leakdown test......

 

Not sure about the details of the cracks but maybe it passed the leak down due to the cracks being up in the intake runner and it was missing from pulling air and oil through the valve spring area? Pics of the cracks would be cool.