1984 50 hp outboard bogs down no power

I have a 84 50hp outboard on a 24' pontoon. I had to replace the gasket on the bowl of the top carb. I pulled it off to check the float. Found this to be a problem after boat would not start. Now the boat starts and in neutral idles up to full rev., sorry don't know rpm. When put into drive it runs slow, under 10 mph. No problems last year with it would do around 20-25 mph. When adjusting the throttles after running full boar and only getting up to 10mph, it bogs down more and sputters. If I stop for about 15 minutes, it goes right back to the under 10 mph. This is my first boat and im kind of familiar with small 2 cycle engines. I would like to figure this out and fix myself if someone could give me some ideas of what to look for. any and all help would be greatly appreciated.