Over the weekend, I ran my 1972 2 stroke outboard on my 15ft classic fiberglass boat. I ran it for about an hour and she ran great. Later in the evening, we took it back out on the lake and while running at full throttle I lost about 50% of my power. While trying to get it running normally (in neutral) it died and turned over great but wouldn't keep running. No smoke, no knocks, no abnormal noises. Same fuel (started with fresh gas and oil mixture 50:1. Any ideas what would cause this to occur suddenly?