If you haven't already, drain out any "old fuel", drain carburetors
(screw on bottom, usually) and if possible clean, or have someone
clean, the carburetors, in case any of the tiny passages are blocked.
Put in new fuel and it should run.
The ethanol gases might dissolve some rubber seals but they do not
hurt the engine otherwise, nor does high test, for that matter. The
most probable cause for outboard not "running right" after a winter in
the garage is clogged up fuel system due to gas evaporating in the
tank and carburetor and leaving sticky gunk that clogs up the works.