I have a 1191 FOrce 150 with an overheating problem. I have replaced the water pump kit which included new impeller and gaskets. Seems to pump water with hose attached but not adequitly enough and when boat is at the launch in the water it overheats quickly and doesn't seem to pump. Has a new thermostat-took thermostat out and flushed out with hose-water ran freely with no obstruction. Any ideas, please help!!!