Pump out the old fuel because Stabil will not work for more than about 45 days. Put a can of Sea Foam in the new fuel. I would change the water pump impeller and lower oil. Pull the sparkplugs and squirt a little Kreep, 2cycle oil or Marvel Mystery oil in each cylinder before starting. Charge, check and clean all battery`s. Visually inspect all fuel and oil hoses.
“The world will not be destroyed by those who do evil, but by those who watch them without doing anything” GOD IS GOOD