As you found, plugging in is going to be your best bet.
Unfortunately, an outlet is not always available. When I am at a customers, I can't plug in. Not an issue if I'm only there a couple of hours, but more than that and it smokes like a train. Occasionally, even after being plugged in, it will be idling fine and then it wil start missing and idling rough. I shut it off and start it back up and it's fine.