Hey Green,
With a big-a** socket, check the tightness of the bolts that hold on the clamps that hold on the anti-sway bar...mine were a little loose and did the same thing. There's probably a torque spec but "loose" isn't it. They may not look loose either--take a wrench to them.
Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America