body twist please heplp

I have 1986 300E manual with 200,000 miles. I have a proble , when I am driving at any speed and I downshift to accelerate The whole car twists the backend jerkes to the left and the front end wants to take off to the right. I assumed this was a suspension problem because everything was original. I replaced the Motor mounts, trans mount, and ,steering dampner. I also put in H&R springs and Bilstien sport springs. I have new differential mounts but I am waiting till I get my rear sway bar before I drop the subframe. Anyway I still have the jerk in the suspension and it is driving me nuts. Please Help!