Yamaha 9.9 4 stroke power loss

Hello. I have a 2001 Yamaha T9.9ELHZ outboard. Starts and runs ok, gave the carb a cleaning etc as it stalled sometimes at low rpms and now it runs and idles great, BUT wont rev all the way to max rpm or even close to that. It seems that once you open the throttle to mid or more it bogs down and has no difference in power at all. It will no only push my sailboat at 4 knots at full throttle whereas before it would do hull speed at 7 knots.

I have checked all the obvious stuff. prop ok etc
new fuel filter. new fuel. new plugs. new oil and full service (by me...)its cooling properly
new water pump. no difference with automatic choke in or out

It seems from what ive noticed that its almost as if it has a manual choke that was left on by mistake and thats accounting for the power loss but its a fully automatic choke and there is nothing to adjust etc. I have also adjusted the fuel screw and carb etc to lean and rich etc to see if that solved it but no matter what the lack of power persists above mid throttle.

Any ideas anyone?


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