Overheating Problems

I have a 1996 Buick Regal Custom with 3.1L V6, 208,124 miles on it. Yesterday my wife was driving it and while at a stop light it stalled out and the temp gauge went from 1/4 to pegged out in the red in just a matter of seconds. Steam pouring out of under the hood, and would not start. I went to pick up the car and it started fine, temp was a little over half. Once moving temp dropped to 1/4 on the highway. As I slowed to a stop it stalled. Restarted, next stop sign stalled again, and temp pegged out steam again pouring out. Now no coolant leaks are visible anywhere. However, the coolant reservoir does keep going dry. I checked the oil no coolant or other signs of problems, normal looking oil. I pulled 1 spark plug, normal there also. The water pump bearings are making some noises but are still spinning freely. Also, there is hesitation on start up for a few minutes then it will level out. No idea what could be wrong, any ideas?

Thanks