I have a Nissan 5 4 stroke outboard attached to a jon boat. It stays in Maine, and goes through some rough winters but it stays inside out from the elements, it worked the past two years great but when taking it out this year it started great in idle, but then when putting it I drive it ran great for about 25 seconds then stuttered and cut out. If you let it sit for a few minutes without messing with it, it will run for 5 seconds than stop. It runs great in idle, but then when put into gear it will die after a few seconds. We have replaced the fuel filter, cleaned the carburetor, replaced gas, checked gas line and pump, water cooling works, oil is good. Could it possibly be the spark plug? We looked at it and it seems fine, the model of plug is NGKDCPR6E.