First off check for broken impeller do this by checking coolant flow with the radiator cap off & looking to see if the coolant is moving with the motor at about 2,000 RPM or pulling the pump cover. Make sure you not idling to long and you have the proper jetting.
Good upgrade Billet impeller & billet pump gear, over sized radiator, using engine ice.
Here is a site sponsor that you can get the billet impeller & gear from. http://mullengineering.com/