I've been giving this some thought. Crazy problem you have here. Only thing that kills a plug is gas fouling, an old car trick was to just set the plug wires on the dist cap to make an air gap for the spark to jump, supposedly increasing it. So possibly you have weak spark and it simply won't fire a used (wet) plug. No one here likes anything electrical except OEM for the most part. I'd swap out parts individually with a friend if possible. Ohm test the plug caps (they have a built in resistor) Someone in recent memory had a new one that was bad.