One day, I had a similar symptom on my CT3 of running until it was warm, then stalling, and not being able to run beyond idle. After fooling around for awhile, I realized that the choke was still on (duh). Not that you would do this, but you might check the choke circuit to see if it is somehow leaking extra gas when not needed.
Another problem that developed was a small amount of rust on the flywheel cam where it rubs against the points. It didn't take long to wear the contact part of the points so that I had to adjust it. Over a matter of hours it would run worse and worse and finally die, and I'd have to adjust the points again. A new flywheel fixed that.
