Hi Mike,
I 1993 Altima and also have the same cruise control problem and the same symptom and historic of the problem.
I've check everything, and all seemed fine. I suspect it's the ASCD (Automatic Speed Control Device) control unit that is located just left of the driver fuse box. I removed it and opened it and check for any sign of bad solder or component burn but did'nt find any. But I'm pretty sure if the source of the problem.
Did you fix your ? Was it related to the ECU ?
Thanks