I would imagine after 5 years you might need to clean and/or re-build the carb. Have you adjusted the needles lately? I would have to guess you had two lean runs. Where did you take the temps after landing???? Never heard of one cylinder not getting lube, but one will always run a little leaner than the other. If you are lean, that's the one that will burn first every time. Muriatic acid works wonders sometimes