Go to the local parts store to get the mounts. They don't cost much there and they may even have them in stock.
Having a bad motor mount will allow the engine to move or tip to one side more than it should. The movement over time can break a wire inside the insulation where you can't see it.
So try the jumper wire for grins and giggles.
If I were a betting man you have a bad wire that provides power to the coil.
