Do you have a Tune in your ECU or is it the stock flash?
Knocking is unusual if it's stock, the timing is VERY conservative from the factory, I got 10+ degrees spark advance over stock all through the powerband at WOT running 93 Octane with a Custom tune!
Did it just start doing it? Maybe a bad tank of gas? Are you running 93? If you had a Predator Hand Held Tuner you could Datalog your Knock sensors to see if there performing correctly, but with the right Octane and timing that shouldn't even be an issue, lots of guys turn their Knocks off in the Custom tune!
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1999 SVT Cobra 4.6L Engine Knock 
