Bucks is a bit vague of a description. It the engine surges and revs up but grabs again, then ventilation could be suspect. If the engine dies and recovers, then fuel filter, pump (low pressure) or water in gas would be high on my list of things to check out.
I got thinking about what buck could mean and I'm wondering if you might be referring to porpoising, where the bow of the boat bounces up and down while on plane.
