My wife was driving home yesterday in the rain, and the speedometer started bouncing between her speed (65) and 80. Anyone know where the speed sensor is so I can check the wiring connection? Anything else it might be? Would that affect the performance of the engine in any way?

 

VSS, ontop of rear differential

 

Turned out that the speedometer bounced when the wipers were on, not just when it was raining. A pinched wire from the wiper motor under the cowling had finally separated.