It’s very likely the lift. More specifically, it’s the steering geometry of the Rough Country knuckles.
After completely wearing out a set of front tires in 2,000 miles, while having mine in to 4 different alignment shops, and noticing really sketchy handling while hitting a bump at speed while turning, I called Rough Country. Turns out, at some point, they redesigned their knuckles. The Ackerman was all wrong, causing the toe to change depending on steering angle. On an alignment rack, it seemed fine, but real world driving, it was awful.
Rough Country sold me a new pair of steering knuckles, and after another alignment and new tires, the truck drives better.
I still hate the Rough Country life, and am considering taking it off to go with a BDS.