Solved your problem...don't go faster on the street than you can trap in the 1/4.

Which shouldn't be over 100.

Therefore...quit going into 3rd @ WOT.

Or, it's knocking like a b1tch...there is TONS more load on the motor in 3rd gear than in 1st/2nd...my advice...get a way to scan it and see what is going on and stop beating on it.