Edce, You mis understsnd me.

I wasn't suggesting they would be. It was a comparison of faults.

A bad ground will generally cause a 'ground loop'. The effect of which, is differing voltages on the system. This can cause the symtoms you are experiencing.

May not be of course, but generally, the first place to start looking.

I was told that electronic ignition needs a very reliable 12v input. Do you have the more modern (solid-state?) voltage regulator? Or the old one with contacts etc?

And thanks for the answers about sparking plugs. I had no idea.

I have an electronic voltage regulator. Tnks for interest in the subject.