9.9 honda issue

[Glecky01]

Hi my early 90s 9.9 will start and run fine most of the time, but every now and then it will start to chug. It’s like it is only firing about every 1 to 2 seconds. It won’t stall but will chug like that for a time and then start running fine. It will do this at all speeds (idling at dock, running slow down the river or full throttle) I had a Honda mechanic look at it and clean the carb, and replace the fuel filter. The fuel hose is new, and no one seems to know what is causing this. What should I look at next? Can you please help?

[boats.net]

Can use a timing light to watch for misfire to see if it is misfiring.