I am in the process of hunting down a part throttle/WOT knock,
I have tried to eliminate as many causes as possible.

I believe that it may be caused by a lean condition.
The Performance Resource Chip that I originally thought
was the culprit ended up as a dead end.

I switched the chip back to the stock piece and set the timing
1 degree below the factory setting @ 5'. New plugs and new
wires. Have also ran 3 cans of GM Top Cylinder cleaner through it.
This is with 93 Octane in the tank.

Still have the same spark/pre-det. knock at the same places as
before.

Back when this test was made, I was able to borrow a TECH1
briefly to verify this. No longer have access to it though.

The Plenum, Lower Intake and TB have fresh gaskets, vacuum
hoses have been replaced, brand spanken new EGR Valve, MAF,
and FPR checked at approximately @ 43 PSI at WOT. TPS@.54
...and still no change.

No codes stored.

Does anyone know if a bad IAC can cause a lean condition?

Any other ideas would be greatly appreciated.