I recently acquired an old sears roebuck 5 hp outboard, which i believe to be a 1971 (definitely a 70s model). The engine runs, but when I start it, whether its at idle or full throttle it is constantly picking up and stopping. I'm not exactly sure how to describe it. It'll throttle, idle, throttle idle, like in burst of speed, and then eventually if it idles too long it will die out. Is this a fuel problem? I've recently cleaned the carburetor but who knows if I did it right. Thanks for responding!