I have worked on many Ford vehicles. I have replaced, lubed or what have you to correct these conditions. Nine out of ten times it is the speedometer head unit. Ford has many problems with the bouncing speedo. Mine does it also at low speeds. I believe it is one of the counterweights that came loose. I have a 160 speedo i have yet to put in. I bought it used and it is getting calibrated by the place that calibrates the NY State Police vehicles.
This is a common problem on Fords. The only correction I know of is getting a new one or getting it repaired.
James
__________________
Cobra brakes are on! Finally.....
------------------------------------------------
|