INTERMITTENT IGNITION ISSUE

Run the car, monitor battery V and don't let it climb (use RPM) to keep it below 16 if it goes that high. Warm up the engine, the engine bay, and battery, and get it charged "normalized." Then, at idle, at fast idle, and at "medium cruise" RPM notate battery voltage. Should not be above 15. Turn on loads, headlights, heater, etc, and re-check.

You need to take a systematic approach.

These girls are SIMPLE compared to Fraud and Generous Motors with the old 4 pin idiot lamp VRs