V-man?
Do it please...
One simple way to determine if the spark plugs were causing the “problem” is to put the same plugs back into engine. 
Sure...just thinking maybe you could come help..
Currently back home( I am in Southern GA right now) it is -5°C( 23°F) snowing with freezing rain. We should only have to stand out in the driveway for an hour..to swap the old ones back in..
