Try checking the speedomoeter cable - Just fixed mine!
1) Get a chilton's or similar repair manual
2) Take the necessary dash components and remover the instrument cluster
3) There will be a few attachments in the back of the instrument cluster. Remove the speedometer cable (undo the locking tab), speed sensor (there is a screw), and gear shift indicator (there is a chip to the column shift)
4) check the speedometer gauge by putting a pencil or somthing into the socket and spinning it. If it binds and makes noise, replace it (good luck finding). If it's good, pull the cable out (wacth out, you dont's stain the interior)
5) If it looks good, pull the cable out and clean it with brake cleaner and a rag. You may want to disconnect the cable housing from the transmission so you can shoot the brake cleaner in the cable housing.
6) Take the clean cable and grease it by placing grease in your had and rubbing it on the cable, then stick the cable back in the housing. Grease about 3/4 of the cable. Try not to over-grease the cable.
7) put everthing back. If any of the gauges don't work, check the electronic connector to make sure there is good contact.