I have a 1992 cutlass ciera SL. It has 61k miles. Recently the speedometer will quit working during a drive. This does not happen every day. I can be driving and the speedometer will be working fine and suddenly drop to zero. Sometimes it will bounce back but usually stays at 0 mph until i turn car off. After a few minutes it will be fine and then could suddenly stop working again. as I said, some days I will have no problems with it. I have had the speed sensor replaced and has not helped. what could be causing this?? The only other thing that may be related is the fact I can be traveling at 30 or 40 or 50 mph and let my foot totally off the gas pedal and the car will maintain speed for an extended period of time before slowing down - maybe 20 seconds or more.

Suggestions??