I have a 2004 yamaha 50 hp carb 4 stroke that is idling to fast. It started last August after a trip to Winnie. Lowest Trolling speed was about 2 mph at 700 to 800 rpms now it is 3 to 3.5 mph at 1000 rpms according to my rpm gauge. When I first start the motor the rpms go higher then normal also. Anyone now of a fix or something I can try.
My 40 Yam has 3 carbs as well…before I started using SeaFoam there were some issues with jets getting clogged. The seafoam took care of all that…I can’t speak to your particular issue but sure looks carb related and if nothing else changed, then something in those carbs must have gotten gummed up. The automatic enrichment system (choke) makes mine run slightly faster when cold but it settles down to normal pretty fast as the engine warms.
Could be something as simple as air leaking into your fuel line. Usually at the connector. Sometimes its a pin hole in the hose.
Could be a sticky choke.
If you can pull the hood, put the motor on the garden hose and warm it up. Then spray the heck out of carb intakes with gumout and run a can of seafoam through the next tank of gas. Might fix it.
Could be clogged slow speed carb jets.
-J.
Both suggestions above are on the money…also look at your linkages when you twist your throttle. Do they spring back fast? Or do they slowly return to normal? You can try carb cleaner on them as well. DO NOT OIL! It just collects dirt and gunk. Make sure none of the linkages are rubbing on others. Let us know what you find out. 
I sprayed the carbs with gumout carb cleaner and fished today for the first time sense. It really helped, boat started first turn of the key and rpm’s where normal. Thanks for all the advice.
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