I have read all 20 pages of this
why........
cuz my turd is doing the same thing
i have all these mods so i never noticed it until i got a wide open space at 3 in the mornin

Alot of you guys say your wires and plugs were the culprit
but me....i am the proud owner of a delteq coil pack system
i will never change the opti again..GM should pay me for ever seeing that stupid invention. All of us have adjusted our own valve lash
I really think that is the problem and ive already played with them 6x
Where do you purchase the hydrarev kits and are they really worh it
My dyno run says i break up at 4700 and really bad
Vibrations are worse than a mack truck but only after it breaks up
still put out 315hp at 4500 on the dyno tho