Try logging TCC slip in your Scanner and seeing what occurs on that end when letting off the throttle. It could be the TCC locking/unlocking too quickly. I had issues with that in my 12 Impala (3.6 w/ a 6T70) and it ended up being the desired slip and the pressure ramping in and out. Additionally, that Torque Factor you adjusted only affects the transmission's upshifts, typically people don't go below .6 (or 60% scaling) for longevity concerns (deceasing scaling can lead to more load on clutches during shifts). I find that between .8-.875 (80% and 87.5% scaling respectively) feels best during shifts (if shift quality is a concern for you). You'll want to look at your Engine torque management if you still believe it is torque management causing your issue. I saw one event in your end3.hpl file at time 4:01 where it appeared to be a torque converter slip change after a WOT pull as you were letting off the throttle.