My car’s rear feels like it sways when you hit bumps in the road. It has 77,000 miles on it

Hello. No, do not try to modify the factory suspension on this vehicle. If they found no problem with the operation of the system, it would be best to check a few more things. First, tire condition and air pressure. Make sure the tires are in great condition, not too aged (less than 6 years old) and inflated to the factory specifications as listed on the driver's door jamb tire placard. Secondly - check the wheel alignment. If the rear wheels are not aligned properly, the vehicle will not handle as it should. This is worth checking into. Good luck.