Ken,
The distributor modual takes the crank timing off the cam. I don't know what a dual sync is other than maybe two pick ups like the older dual points distributors. Noise will degrade the signal. A cold solder joint in the modual or bad solder will case it to drift once the engine starts to heat up or not work at all. Your Motoc is a good unit, run the diagnostics on it. I doubt it's the ECM. Even distributor gear wear will cause drift or shaft bearing slop. I know the Motec has logging so check the log and see if the setpoints are constantly changing or resetting. That may give some idea where to look.
Dave
