I bought the '17 Yukon (5.3 6 speed) used and noticed AFM right away. Cruising along, especially at lower speeds, a little throttle tip in and feels and sounds like it's lugging. Blackbear tune and I was thrilled, tuned off the AFM, fixed the weirdness with the trans shift points, night and day difference in drivability. Corsa sounded good at all times instead of the helicopter sound during lugging. Very little to no drone from that exhaust though, regardless, which was impressive.
I was optimistic with the '22 Tahoe (5.3 10 speed) DFM. Didn't notice it at all first 7,000 miles or so. Now, same thing as AFM, lugging. The miles, the time, the first oil change, the colder weather, a stack up of all these variables but now it's here on my Tahoe and very noticeable. Blackbear seems to be a no-go, checked in with them earlier this week. Range isn't saying no, but if blackbear can't is it realistic they can? I tried 89 octane and noticed a slight improvement, running a first tank of 93 now for the heck of it incase the cylinders that are firing when DFM kicks in will misfire less with the higher octane (grasping at straws). Could cause the opposite problem and have DFM kick in even more with the higher octane though. We'll see if that helps. Also have a bottle of the ACDelco injector cleaner coming, the one recommended in the manual. Can't imagine I have buildup already, gas I run isn't top tier but it's a newer and very busy gas station.
Last resort is running in L9 as it stops DFM (and auto stop/start which is nice), just don't love losing a gear as a "solution" and I'm not sure I like what the transmission is doing in L9. We'll see, that might be what I end up sticking with if the 93 octane doesn't do the trick.