i did a search and got nothing.

my speedometer accelerates fine, but as soon as you hold a constant speed or let off the gas (say going down hill), and slow down the needle bounces all over the place and occassionally just drops to zero.

 

replaced the cable twice now with no change.

 

i'm assuming the instrument cluster needs replaced?

I think you're right about possibly needing to replace the entire cluster.I think that will have to be done to fix it.