I think it’s at all speeds.
Another clue I just remembered: I first started it in the tank yesterday and the cut-out switch worked as expected when I revved it. I didn’t rev it much because I was messing with the carb adjustment screws. But the longer I worked on it the less it wanted to rev and the cut-out just seemed different. I attributed it to an inability to rev due to a fouled plug.
I figured I should just get it on the water with a new spark plug and let it run. Looking back perhaps the cut-out was disabling my bottom cylinder?
