All the sudden the speedo needle would bounce around and is very innacurate at time. I can be doing like 40 and it says like 15. At other times it works normal. Any ideas ?

 

my girls does the same thing , and the one on my b16 doesnt work at all !

 

Check the plug connection.. if its loose it will do this also

 

yeah check the plug.

it's the giant plug sitting on top of the tranny. right under your intake arm. pretty easily accessible.
unclip it out, and clip it back in. make sure it's good and snug. sometimes that's all it takes.

 

connections may be loose or filled with grease/gunk. When that happened to me, I sprayed mine with engine cleaner and rinsed clean. Its working perfect now.