1981 Honda 9.9, 4 stroke o/b, Idle problem
I have 79 7.5HP Honda 4 stk. It was suggested to me that these sort of things can happen if air getting into fuel line. Something to check anyway.
Another thing pointed out by Honda technician. These motors do not like to idle at very low throttle. While they will do so it is not teh best thing for teh engine.