2001 DT115 overheating

[gone_south66]

I have replaced the thermostat and water pump ,grommets on the tubes and I still cannot get it to stop overheating at high rpm, sometimes it will run for an hour or so then the next time it only takes a few minutes to overheat, it has a great stream at idle but high rpm its sputuring not enough staeady stream ,any suggestions I have read a dozen forums and nobody seems to have the same answer, but I did do the new water pump and plate, and a new thermostat , should i do the head gasket ?

[acbaer]

I had an issue with my 96' DT115 overheating. Mind you the boat was new to me, but my Pontoons has 500lbs of Water in them. I drained that and things seem to be running a lot smoother. I wonder if you you could be having something like that depending on the type of boat?