The answer is in the name: 4K. Tow capacities are determined under pretty extreme, brutal conditions, such as steep gradients and high air temperatures. Your dealer is just plain wrong. the 4K package means you can tow up to 4,000 lbs.
The question is although you paid for the 4K package...
In the FX4/Tremor models, the driver can manually engage 4WD. The AWD version does not have this feature. The computer will decide how much power to send to the rear wheels.
Maybe try L instead of D when selecting gears.
What TJ2023 said. A good chance it won't be covered under warranty (especially since it sounds like you bought the vehicle second hand.
If you replace the axles and keep the lift it will happen again.
You know men lie about three things. (1) how tall they are. (2) what their golf handicap is. (3) how long their shlxxng is. The seats are not the most comfortable I've had; but they're not uncomfortable.
Women also lie about three things but that's a another story.
When you install the damper you will need to remove the lefthand tailgate tie down (aka bottle opener). You can purchase ones compatible with the damper from amazon (but they won't open any bottles).