Eight years later my engine was running very rough, like it was about to stall and then keep accelerating. There's a lot of talk online about the carburetor but I figured nine years later I might as well change the spark plug and get an engine/carburetor cleaner too. Plugged in the spark plug and everything works. After that a STABLE engine/carburetor treatment was added so hopefully this will fix the carburetor issue in the future.