Our local youth sailing non-profit had this engine donated and we're trying to get it running right. I changed the crankcase oil, checked the lower unit oil, changed the spark plugs, cleaned a bunch of goo out of the carburetor bowl and main jet, set up a tank with new fuel and have it on a good battery with a hose on muffs for cooling water. It will start easily and run only if the air intake is restricted with a thumb controlling the amount of air flow available. As long as the air intake is restricted and adjusted finely with your thumb the engine runs very nicely. It seems to me that this indicates not enough fuel for the mix, but I can't figure out where the restriction might be. Any ideas would be appreciated.