I have a buddy that has a 1999 Ultra with a Marine power 454. All stock except a MSD box on the stock dizzy. When he first bought the boat last year the temp. gauge ran at 140 all day, now it is showing 180 and up. We cleaned out alot of sand from the water jackets and replaced all the water hoses on the engine but still ran hot, if he stays under 2,800 to 3,000 RPM all is OK but if you go over that it start to heat up! What else should we look at?