engine cut off after 2500 rpm and overheat

I have a honda marine engine 200 HP 2002... my engine run good for 2 miles after 2 miles at 2500 rpm cut off and the alarm start to beep. But when i let it below 2500 rpm runs goos... i put the computer and everything but this drive me crazy... i already changed the gas filter , the thermostat, gas pump... also has a small leak of oil but i think is because i get overheat too many times... i wonder if my problem can be no enough water in the engine , because it happen just after i run my engine over 2500 RPM ...some mechanic told that i need to replace power head... can some one tell me what cause it can be ... thank you

There three different alarms - continuous, short beeps, and long beeps. Which are you getting? Does your key switch panel have 2 lights or 4 lights? Which lights are on when the alarm goes off?