I'm working on a 2003 Cavalier. The cruise does not work, but I suspect that is due to the failure of the speedometer.

The car was purchased in spring and worked fine for just over a year. Starting that summer, the speedometer and tach started to function improperly. They worked sometimes, but not others. Not working consisted of not displaying anything or being inaccurate. When the car ran for 10 - 15 minutes, the guages were more likely to work properly. It is now the following winter and the guages rarely display anything. When they do, they're usually incorrect. Sometimes everything works fine, but usually doesn't and is hard to draw a pattern.

I've been told sensors, computer, wiring, and the instrument cluster are to blame. That doesn't leave much else to go wrong. Ideas?