Thanks for the update!
I just narrowed mine timing doing the same thing around AE and PE events. Mine is set at 9.8° initial mechanically and in the Main Spark Bias scalar.
My timing was actually going through the roof; I felt the power drop, had hundreds if not thousands of knocks logged during the spikes, and the timing was logged as trying to retard 48°.
I will try setting back to 0° tomorrow and see what happens.

1993 Chevy Blazer
5.7L with Summit aluminum heads, chevy performance roller cam, bored tbi, shorty headers to single flowmaster