1994 Mercury Marquis Cruise Control Stopped Working

The Cruuise Control stopped working. It had been working fine for years. It was intermittent for a short time, (it would turn on by pressing the activate, or resume button), but then it stopped altogether. I do have power at the on/ off switch and when pressed on I have power at the activate switch, (the switches are on either side of the airbag on the face of the steering wheel). I replaced the speed sensor on the transmission. The cable from the cruise control box to accelerator is free and not sticking. I do have the check engine comming on and off at intermittent times, but no fault code is set, and the times do not seem consistent with any driving actions. Does the cruise control rely on the Computer? I replaced the computer some time ago for intermittent faults like the ones I am finding now. The Brake Switch on the Brake pedal seems to be working appropraitely.