+1.In short, you probably need a retune.
I also wonder about fuel grade/quality.
Similarly, I wonder about potential mechanical issues - aside from the outright mechanical problem, I wonder if either the knock sensor is corrupt and/or, if anything is tapped in to the ECU pinout for the knock sensor lead, i.e. a "knock-light" device, if either that device or its unshielded wiring could be causing feedback sufficient enough to corrupt the knock reading (don't laugh, this is actually very possible, and is exactly what happened to several early adopters of the TurboXS Knock/Shift-Light on the BL/BP Legacy).
Finally, can you pinpoint where the car's pulling timing?
Something big is going on, if it is severe enough to drop IAM......