You didn’t mention anything about the spark plug wires so it might be worth checking the spring connector inside the boot for corrosion and the wire itself for continuity with a multimeter. It’s amazing how much trouble a bad connection in the boot can cause. As for spark plugs, try a set of NGK’s. You’ll be glad you did.
Slowing down after planing for a minute and then catching its breath after idling for a bit sounds like a fuel delivery problem or possible overheating issue. With a new fuel pump, it could be sucking air in at the hose connectors either at the tank or the motor end. If the connector looks like this one, it can be taken apart and a new O ring installed.
