I guess I posted the outcome of this situation in another thread. The distributor was shot. Also the car had the original cap, rotor, and plug wires, which were age deteriorated. (the car is '91)

At random times the bottom gear end of the distributor would land wrong, or would get off time, causing the resulting situation you describe - no/weak spark to 2 or more cylinders.

The thing that finally killed it, was a leaky radiator was spraying coolant directly on the distributor.

Thanks everyone for your help.