at around 40 to 50 mph im getting a bounce. I feel like im driving a freakin 18 wheeler in the seat! Not the tires, front end isn't out of line. It stops around 52 mph. It does it on any road new or old. Any thoughts on what is causing it. Its a 2004 OR 4x4 crew cab, I also noticed my wife's armada does it at around 20 mph. Im baffled.