Your transmission might be shifting weird because you’ve been beating on it.
Check the transmission fluid, look and see if mkultra supports your TCU (doesn’t look like it), depending on the year and transmission there’s an issue where transmission fluid will start wicking up the transmission electronics connector and get into the TCU and cause issues there.
Did you ever do a re-learn via xentry/das/whatever after changing the rear size?
Your transmission might be shifting weird because you’ve been beating on it.
Check the transmission fluid, look and see if mkultra supports your TCU (doesn’t look like it), depending on the year and transmission there’s an issue where transmission fluid will start wicking up the transmission electronics connector and get into the TCU and cause issues there.
Did you ever do a re-learn via xentry/das/whatever after changing the rear size?