Hard 40 mph shift in 65 tow

[Highbeam]

2000 auto powerstroke.

So I got to tow the big trailer with the family this weekend in the 65 tow setting. The RV trailer weighs about 7500 so it isn't really that big. Truck has 168000 miles and looks to be original trans. I am coming from an NVK4 PCM so I have read that the shifting will be way different.

I really do like everything that the chip does to the shifting except for the shift that happens at about 40 mph. Whether lightly loaded or climbing a hill that shift is very hard like being rear ended and the whole truck lurches forward and then bounces against the drivetrain like I dumped the clutch. I am not sure if this can hurt the truck but it is a hard hit. The next shift is up near 50 mph into fourth, that shift is firm but not a slam.

Is this a hard TC apply? I don't really feel a slippery (unlocked) third gear and after the slam I am locked in third.

Is there something I can do to soften that 40 mph kick? Could this be a sign of a questionable PCM connection. I never did disconnect the batteries for a "relearn" after adding the chip. Fluid level?