no power

hi Guys,

New to this forum but am despertly seeking help/advice
my 200hp saltwater 2000 V6 (not fuel injected) outboard has been giving me problems for the past six weeks (am on the hard for six weeks ) whilst seeing my friends fishing and boating i have been sweating and swearing about a problem that three mechanics cant solve, so i am looking for some help from anyone out there who might have encountered this problem.

my boat is a 24ft racala with top speed of 36/38 Knots all of a sudden the boat cant go more than 6 knots loss of power, the engine is running very smothly on idel and can rev it up to 6000 rpm on free but on gear it cant build up more than 2800rpm. so first to make this short we have checked and changed the following

petrol
petrol filters
sparkplugs
2 coils
2 thermostats
Prop housing
Cleaned Carburators the three of them.
impeller and impeller seal

But the problem persists, any one had this problem? as my three mechanics are at their wits end. and im still on the hard.
thank you in advance for saving my summer.

Re: no power

just to keep u informed if anyone is interested, we have now checked the gear box and found a seazed bearing which we have changed and shall be trying out the boat on monday so will keep you informed.