There are many and various options for the solution to this problem. However, some of those fixes may be as simple as a radiator cap or a belt tensioner slipping. Another problem may be the water pump impellers are wore down. Also, if you are accelerating at a high rate, the vacuum may be leaving the blend door or the control panel and allowing the door to move to an improper position.
Gerald Wheelus
Edgewood Auto Parts #253
Edgewood, Texas