my speedometer is messed up, it bounces from 10 -50 mph, any sug? i just wana un hook it.

 

right now my truck is all messed up and i think it is from the tach sensor. i ripped out the wires when doing my head and when i tried hooking it up all different ways with the 3 wires one or 2 of the times my speedo jumped around like that so maybe check out your tach sensor it goes off the harmonic balancer the plug is right at the front of the head.