I have a strange problem that my car has had for the last 8 years that not even 2 seperate BMW Dealers and various independent mechanics have been able to diagnose.

1991 535i E34 with 173,000

I bought the car from the original owner and he told me of the problem as he tried to get it fixed as well.

If I am driving between 50-55 MPH, all of a sudden the car starts to shake like if someone is hitting it from behind. This happens only when I am not stepping on the accelerator too hard (just cruising). I had the transmission looked at and have replaced fuel and air filters as well as the spark plug wires and new plugs, but nothing has changed. Once I step on the accelerator harder and speed up, the problem goes away. The same is true if I let go of the accelerator when the car starts shaking.

My cruise control sometimes kicks me out at whatever speed I am going so I don't know if it's related to this problem at all or not.

Later.

Mainnor