Loose rear end
 

I own a 05 clk 320. When making a left turn my right rear end is loose. Especially when at a high rate of speed. It feels like the right rear tire is flat. My tires are brand new and have the proper psi. I have no problems when turning right. The left rear feels good. I did the bounce test on both sides of the rear of the car. It rebounds fine and didn't bounce to much. Both sides seem to be equal. So I really don't think it's the shock. What else could it be? Can any one please help?

leaking shock, bad suspension parts maybe, alignment issues. tire pressures, accident previously.