I have a 2008 V-6 Dodge Charger. The past month or so I have noticed a very pronounced rattling noise coming from the front end. It seems to only occur when driving over rough and bumpy roads, never on smooth flat ground. No noise is heard when the car is still and I'm turning the wheels. Today I took it to a shop. They checked ball joints, struts, strut mounts, sway bar links and bushings, a arm assembly, tie rods, steering rack...Just about everything in the front end. They even checked for loose body panels, heat shrouds etc but could find nothing wrong? What could it be?