They are admittedly difficult to see in bright sun but you could try an in-line spark checker to see if it is loosing spark when it stalls. Maybe go boating at dusk when it’s easier to see. Maybe a condensor is going bad?
When it stalls; does it re-start immediately? Do you pump the primer-ball before a successful re-start?
here’s what I’m talking about:
https://www.harborfreight.com/90-in-lin … 69023.html
