Re: 86 Suzuki 65hp
I had an early 80's suzuki that had some deteriorating foam that lined the engine cover.
I could clean out the float bowls and jets only to have the issue re-appear sooner or later. Usually sooner.
Many times something as simple as a run home and back to the water, or even stopping and fiddling with anything, might dis-lodge the debris from the main jet and it would be all well momentarily, only to rear it's ugly head again.
These bits of foam would easily find their way in through the carb bowl vents located at the top of the carbs.
After removing foam all together and washing down powerhead and hood. Along with a bowl and jet flush, it was all good.
Remove cover and wipe your fingers on motor. Any somewhat gritty feeling debris all over, or anything oily will indicate this.