hi yall, ive got an 84 300 sd w/ auto tranny. On occansion my cruise control will come on and the car will accelerate. the lever on the steering column will not turn it off but i can use decel/set lever to slow it down, but it will continue if i let off. Please let me know whats going on. thanks eric

Could be either bad solder joints in the amp (common) or corroded contacts in the column switch.

Just completely re-built my cruise-control amplifier and system...

But I believe your system has a different actuator to mine. I have a cylindrical vacuum actuator on the wheelhouse, I think yours is the electric motorised variety...

The 'ECU/amplifier works much the same, But the drive circuit to the throttle actuator is completely different.

Speed set, measurement comparators etc are much the same as is the MOSFET set-speed 'memory' circiut....

Your fault is most likely dry-joints on your ECU circuit-board. BUT BE very careful, and short-circuit the MOSFET connections before touching the board with an iron. The BSV81 Depletion-mode MOSFET is practically unobtainium and is VERY EASILY damaged easily by static Electricity

Speed/time errors (speed drops with time) will be the cap or the reed-relay block attached to the MOSFET flying-lead Gate connection....