Q: Transmission was slipping. Could it be the VSS?

Hi there. For the speedometer to be malfunctioning, either the vehicle speed sensor (VSS) could be loosing signal or the gauge has a bad resister. Now, as far as the transmission slipping, check the transmission fluid level. If the fluid is full, then test drive the vehicle and drive it slow. Let the transmission shift. Then drive the vehicle with more power and let the transmission shift. If the transmission hesitates to take off or it phases in between gears, then the clutches are worn inside the transmission causing it not to hold a gear. If the transmission is working just fine, then there is nothing wrong with the transmission. If you need further assistance with your speedometer fluctuating, then seek out a professional, such as one from Your Mechanic, to help you.