Electronic ignition conversion help.

If you know someone with a labscope check for the alt pattern at the positive to negative posts on your battery. Those alt"s will cause idle concerns if the brushes and rings are worn out. The brushes will float and actually arc causing severe voltage spikes which will affect every electrical and electronic componet on the car. You will not notice this on your gauge.
Another way but no the most acurate way is simple disconnect the field wire while idling and see if the idle smooths out or becomes more stable.

Just a ideal for you to check.

John