Did you ever adjust the clutch pedal or mess with the clutch actuator? There's a push-button on the clutch pedal that turns off the cruise (and won't let it activate) if the clutch is pushed in even a little bit.
Turn on the gear indicator (
http://www.ft86club.com/forums/showp...16&postcount=4) and see if it shows a gear (1-6, because reverse is ALWAYS displayed regardless of clutch pedal position) when the clutch is fully released.
If it doesn't show a gear besides reverse, you've got a problem with either A) the clutch actuator is messed up and you aren't releasing it all the way, or B) the switch is misaligned (potentially if you did the pedal adjustment incorrectly).
If it shows a gear, at least you can eliminate that button from the troubleshooting...