I thought maybe I'd have to drive it with a rock on the gas pedal and limp up to the repair shop in Estes Park, but thinking about it, that wouldn't work, because any time I had to slow for traffic or even go around curves the engine would die.
I got it rolled out of the garage and the hood up. There was my bright-shiny brand-new Interstate battery from last month. And the rest of the engine was all sealed up. These new engines - I can't figure out where the air cleaner is to remove it and look at the carburetor, and I wouldn't know where to find the fuel pump in case that was the problem.
Finally, I located a little cable thing that I could move back and forth in the middle of the compartment, not far from the thing that looked like it holds the spark plugs. Jiggle, jiggle. Start it up. That fixed it, and it's running fine. Must have been the accelerator cable got stuck.

Whew!