We had the same problem with the fluctuating voltage and my mechanic has figured it out after a week of frustration. The alternator in the 1995 riviera supercharged is specific to this model. If you go to the parts store they will sell you a generic 3.8 alternator which will most likely have the Wrong regulator. Have the alternator checked by a rebuilder and make sure the regulator inside the alternator is correct. If not AC voltage can be fed back into the system and will Stall the car at random times as is what is happening in my car. Basically making the electronics go haywire.
