2 Stroke Power Loss

[Carpe piscis]

I have a 96 Johnson 15 hp. Recently, I was motoring around on the Colombia and the motor lost power. It acts as though it is running on one cylinder. With the throttle wide open it runs but with little power. I checked the plugs and one appeared to be fowled. I replaced that plug and then put the boat in the water and ran it up. It ran normal for a few minutes and then lost power again. Upon reinspection of the replaced plug it appeared somewhat wet. Again, the motor ran but acted like it was running on one cylinder.
Any thoughts?
Thanks in advance.
CP

[Boat Doc']

I would suspect you are losing spark on that cylinder, if so the likely problem is the power pack.