If you are seeing kr after letting off throttle your spark table may be commanding too much timing for the lower air mass.
I ended up putting my timing tables back to stock and ran it, still seeing random quick .5-1 kr. My ltft's are a tad lean still but that shouldn't be causing low end kr like that. My PE is coming in quick and the AE has been raised up a good amount.
2001 Regal-GMPP handling, shift kit, tuned, ported Gen3, 3.6, N*, SLP dual catback, Aeroforce
70 Monte Carlo 12.5@109 waiting on new setup