I just had the car aligned, and the problem is not fixed. around 70mph, the rear of the car does not feel stable. it feels like it is shifting left and right. I had this problem ever since i bought the car, but i thought my new tires, and alignment will cure it since my steering was way-off originally.....

I am at 180,000 miles......

what is the first thing to look at ?

thanks,

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1993 300E, 2.8 M104 .....