If the coil sparks it's not the coil, though I did have a coil that would intermittently fail when it got hot, but it failed in either mode. It would work when cooled off. Took awhile to sort it out but I got it.
Eventually you will have to break out a meter and find out what is going on.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.