1986 300e 5 spd.(Manual) car starts to sway and jumps on high speed. I thought that the rear shock was going bad so I bought the bilstien HD shocks for the rear and have it installed in a local repair shop close to my home.Its much stable on the freeway. But when I drive the car I hear stomping noise on left rear when driving on bumps or pot holes. It feels like the shocks are so stiff it sounds like dug dug dug dug it feels the rear is falling apart could it be the installation not installed correctly. The noise was not there before. what part is worned out to make this noise. Im going crazy Please help me if you have any idea. thank you