Occasionally idle will rise, sitting at a stop light for example. This page CIS idle rising w/eng temp??? has info, could be the retard not working correctly.
Starting the car to leave work this after noon and the tach was not moving. After less than 1/2 a mile it started working, normal I guess. This link Tach stopped - advice has some info on a similar problem and checking at the tach.
This link MSD Rotor Mod has info on a modification to the rotor that "might" be necessary when running the MDS 6AL. Also has some other rotors that might work with the sc.