CVO 9/21/2012" The needle is moving back and forth ", does the engine hesitated a fraction of a second ? If it does, then the engine control module might involved.
See this link and use their instructions to retrieve any existing fault codes MIGHT stored in the engine control module.
HouseCallAuto 9/21/2012Do you mean the speedometer, the miles per hour? If that is correct then you need a new speedometer.