Whenever i hit around 75 or 80 in my 94 mtx, my dashboard begins to shake. It seems to move almost an entire inch very rapidly. If i leave change in the little compartment under the radio it sounds like a jackhammer. The rest of the car is still completely smooth, you cant feel it unless you reach out your hand and touch the dash. It also shakes the steering wheel a bit. if i go over 85 the shaking dissapears. This is annoying since traffic tends to flow around 75 so im always going too slow or speeding enough to get ticketed on highways. Any ideas on how to fix this would be great.