Tow haul mode is a weird animal , holds gears for longer periods when accelerating sometimes too long . It also downshifts really quick when stopping causing engine racing to aid in stopping .Also these trucks all have learning transmissions and if you don't use tow haul all the time it acts a little wierd until it figures things out .
My 2016 ,3500 with the Aisian Trans took a good day of towing to work as it should .After that worked perfect for the remaing 6 days of the trip . Then it had to relearn for no trailer and then when it was time to head home it had to relearn tow haul .