My 98 XJ8 with 130k has a shimmy in the steering wheel when I reach 50. Starts light then at 60-65 it gets bad and goes away over 75. New tires, discs, balanced(on and off car), it has been checkedtwice by two different repair shops and all bushing are fine and they say wheel bearings are fine. Please help!! It is driving me crazy. It also seems to ride with a slight vibration at all speeds. It use to be as smooth as can be.