1997 28 HP Evinrude Outboard
(Chippewa Falls, WI)
Engine always start good. After running it full throttle for about 15 - 20 minutes, it slows down sharply to half speed or less. I have changed the two spark plug cables. Plugs look OK. It appears to be running on two cylinders. I've tested running each cylinder individually and each starts and runs separately. I think it may acting up when the engine gets warmed up. I am not sure what causes it to abruptly slow to half speed. Any suggestions for repair, other than taking it to a repair shop, would be much appreciated.