Since Ive had my car, the speedo needle has shook. I finally decided to replace the upper speedo cable and that solved the shaking. I then saw that my speedo was about 10mph off from what it should be. I recalibrated it by driving on the highway and taking the needle off and placing it on 60mph when I was traveling @ 1 mi per min. All seemed well until it got cold. Since then it sometimes would read correctly, sometimes not. I left the plastic cover that goes over the gauges off, and when the speedo wasnt reading correctly I could just tap it to the right speed and it would stay reading the right speed for some indeterminate amt. of time. After getting fed up with doing that, I went ahead and replaced the lower speedo cable. Now my speedo is back to shaking, but only at speeds above 50 mph. At this point I am thinking that I might need a new speedo head or that the cable is routed funny. Any body have any ideas?