2003 250 Hpdi

Hello,
I am purchasing a 23ft boat from a local dealer here in the Houston area. The motor has 92 hours on it and new plugs/fuel filter and fuel/water seperator replaced. I went out on a sea trial and the motor never went above 3400rpm and did not have that power that it should of had. The salesman said something was wrong with the engine and it also ran rougher in idle after 20 minutes of use. He also never primed the bulb as he said you did not have to? Is this true?? He also said it might have old gas in it but they did put Yamaha Fuel treatment in it. I was also told by a good friend that the fuel line should be a grey one and the one on the boat is a black one.I was told that the black one can get to be brittle with the great fuel theses days and can foul injectors. Any help on this issue would be greatly appreciated. I really like this boat but without a proper running engine it is not worth much.

[boats.net]

Probably needs fuel system cleaned and checked out, most likely gas has gone bad. Yamaha uses black hose at primer bulb.

Ok....I dont know much about the systems on these newer motors. If it was an older carburated motor I would say it would be the high speed jets. The motor started and idled ok. But when the salesman tried to get the boat on plane the engine coughed and sputtered and he had to back off the throttle to keep the engine from dying.

Maybe I should just buy a mid 70's OMC motor, they seem to run and run and run....