Honda BF40 2004 Power Loss

I have a Honda BF 40 2004, purchased new, that began to demonstrate a loss of power on its first outing this year after a long Wisconsin winter. Before winter ,I always drain the carbs and fog the cylinders.No changes in prop etc

It starts and idles fine ,but has hardly the power to plane out my 16" boat.As suggested by many of you on this site more knowledgeable than I about these things, I replaced the fuel filter, installed new spark plugs, pumped Sea Foam into the system, and now most recently pulled the intake manifold and carburetors to do a more thorough cleaning. At the same time trying to do some fishing in between the trouble shooting.The carbs really didn't seem to be dirty, none of the goo Ive heard could be there. The #3 did have a small amount of the green powdery brass corrosion on the main and jet nozzle ,but it was just a small surface amount and didn't appear to occlude any ports or change the shape of the nozzles.
Pumping the fuel bulb has no effect.
Partially closing the choke does cause an increase in RPM and power. I'm stumped, there is really no reliable Honda mechanic within 200 mi

Re: Honda BF40 2004 Power Loss

Your clue is that partial choke makes it run better. In other words, without choke, it's too lean. If it were my motor, I would disassemble the carbs and give them a proper soak cleaning, then see how it runs.

Re: Honda BF40 2004 Power Loss

Paul, Thanks for the quick responce. I have some additional info,,If I keep the the throtle wide open for 4 -5 minutes the speed/ RPM picks up to maybe normal. Then when I troll a slower RPM for a while followed by an attempt to accelerate and plane out, the low power /RPM problem is back. Does this still indicate a carb problem?
If I'm going to pull the carbs again I want to do it right this time. Can you reccomend a carb cleaner and any techique on how to use it? I used an off the shelf spray cleaner the last time, sprayed all visible ports, the main and jet nozzles,and the float valve , nothing appeared that dirty, I didn't really soak for long and didn't use compressed air only compressed carb cleaner which seemed to flow through all parts and ports easily Thanks Again