There is a small lever you can push down to shut off. It's located pretty low below the #2 and #3 intake ports on the outside of the IP. It's fairly well hidden down low. Easiest to reach with a round rod or stick. Push it down and the engine will shut off. It's likely your pod which you can see at this location just above the lever. Not an uncommon failure. Pretty easy to replace and inexpensive. But, it could be something as simple as the vacuum line pulled off.