Kingpin Box Height

[RedCougar]

I had to lower my kingpin box to get into driveway 10% steep. Took our first trip 80 miles no interstate driving. And it felt like it was chucking every time we hit a bump. Driving home from dealership I never noticed anything. We are headed north in a couple weeks and need help.
09 Cougar 5er
11 F250
Reese 15k slider

[JRTJH]

First questions:

What model 2009 Cougar? From the data plate on the front roadside corner, what is the GVW, Payload, tire size?

What model F250? From the data plate on the driver's door pillar, what is the payload, tire size, and which engine is in the truck: 6.2L gas or 6.7L diesel?

There may be more than just lowering the Kingpin box that is causing the issue. I'd suspect that you've loaded some equipment in the trailer while it was in the driveway? I'd suspect that you may be very near (or over) the max cargo weight and the change in kingpin height may have shifted the pin weight/loading cargo may have increased the pin weight and those factors may have changed how your truck "rides on the overload springs/bumper stops" or even the shocks may be worn and not damping road undulations adequately.

Provide the needed weights/capacities for your truck/trailer and you'll get better responses to your issues.

[RedCougar]

F250 6.2 gaser
gvwr 9600
tire size LT275/70R18E

09 Cougar XLITE 26rls
dry weight 6700
payload 3141
hitch weight 1050
tire 225/75 R15D

cat scale weight possible tomorrow