I've had good luck with Chevron Techron D used twice in the life of our 240D. So, when my gasoline powered generator started giving me troubles, one of the things I did was to put fresh fuel in its tank and run some Chevron Techron (without "D") through the carb. In reusing the old fuel, I add 1 once of it/gallon and put it in the tank of my convertible.
The generator, with fresh fuel and new spark plug and cleaned air cleaner, ran like a top.
I've had very good luck with Sea Foam in carburetored engines. They'll be rough running either at idle or speed. Put some Sea Foam in the tank, and they've all been set right without tearing down the carbs. Done this on essentially all my small engines. Fixed all of them up.
Just felt I needed a heavier duty job on the generator and went with the Techron. Sea Foam might have fixed it, too.
Ralph