I've searched this issue on the forum i couldn't find anything that was the same. I'll try to explain this the best i can.... The speedo does the same thing everone elses does with the moving around 70 to 72 to 68 to 73 etc.... you get the point. The catch is that when i set the cruise, the truck keeps up with the speedo making the truck speed up and slow down all the time. Nothing to major, but it's starting to drive me nuts!!! It's a 96 F-150 with an 8" lift and 37" tires(i don't think this is the cause) Should i try the VSS sensor or the P??? the one behind the guage cluster?

Thanks ahead of time!!!

 

Try cleaning the sensor first and if the wiring and plugs are OK then it would be the PSOM.