My '89 has a problem with the speedometer. At any speed below 40mph, the needle will bounce up and down but at higher speeds the needle will stabilize. It's even stable when decelerating, just when accelerating or remaining at a steady cruise at lower speeds. I replaced the guage cluster with a new one about a year and a half ago due to the speedometer needle jumping off the scale at highway speeds. When it did this, I would hear a grinding noise and the needle would go past the 140mph mark. Replacing the guage solved the problem but soon after I had a clutch job done and that's when this problem started to happen. Any ideas?