Hi…. my guess would be carburetion, of course that's always my guest. One of the most frequent problems with any outboard is the carburetor. All the little jets, and passageways means that any little microscopic piece of dirt can give you problems. I would start out with using some spray/liquid carburetor cleaner before taking it all apart. Also, if you do not have an in-line fuel filter I would suggest adding one of those. I in-line I mean, somewhere in between your gas tank and engine.