Carburetor question Yamaha 100hp 4 stroke

[Team Sanchez]

Looking at a boat with a 2000 100hp yami that has carbs and isn't fuel injected. Motor has 165 orig hours. Last owner didn't winterize boat and it sat for 2 years. The guy who has boat now had carbs rebuilt with factory parts. Runs fine at high RPM's but has issue running at low RPM's and motor coughs a bit. Mechanic said boat has to be run under load to break carbs in. Long story short.... Anyone have experience/advice with these yami's? Trying to decide if its worth buying, or will it always be a problem.