Erratic tach

[Brian]

List,
I just ended a fruitless search of the archives and
was wondering if anyone is feeling charitable.  Can
anyone tell me how to fix my tachometer that has
recently started displaying incorrect RPM readings
(usually too high) and occasionally dancing around
wildly?
Could it be related to the fact that my cruise control
recently kicked the bucket too?
I thought I got away from these problems when I sold
my 91 SE that was the same way.  Damn!!  Any input
would be greatly appreciated.
Thanks
Brian
92 SE-R in VA