I have a 1999 Ford Expedition. The speedometer is reading alot higher than my actual speed. Also the transmission is running through all the gears in accordance to the speedometers speed. So when speedometer says im going 15 im really only going 5 and i shift into second whne speedometer says 30 im really only going 10 and it shifts to third. So I am in overdrive with speedometer saying 100mph when im really only going 35. What do i need to do to fix this?

 

we already replaced the VSS still not good