Ive had this problem for a while now and i know several others have as well...I finally got around to fixing it by using a 5-volt regulator i bought at radio shack for $1.50.

Literally just jammed the two pins into the box, and rewired the power/ground straight through the regulator. Problem solved. Thought i'd share this solution for all of you that are sick of a speedometer that likes to dance.



Excuse the mess, its hidden under the shifter plate