Bribenz - you may wish to read my earlier posts. Plugs are new, so is the ovp, distributor and rotor.
I confirm no arcing at any of the plug wires.
I have sprayed engine starter on vacuum connections when the engine is running and no change noted, suggesting no (obvious) vacuum leaks.
Is it the age of the distributor or the number of miles on it which points the diagnostic finger - wear being a function of aggregate fuel flow volume, no? 125k miles is a very low mileage for a car run on gas purchased from high volume, crud free CA pumps.
Or are you saying you have specific experience of this symptom suddenly appearing because of fuel distributor problems? If so, your diagnostic process would be appreciated. Also, why would the engine suddenly exhibit rough running symptoms rather than gradual deterioration, which I would expect of fuel distributor problems, or could check their 1981 380 motor for comparable readings?
Anyone have a specific answer or specific experience of my earlier detailed technical reference to the voltage readout at pins 3/ground and pins 5 & 4, please?