This glass top stove when you turn on one of the elements, it heats up, but then seems to shut down, then it heats up again. So it does not maintain and even heat. It is the main element the wife uses all the time. She says, or thinks all the burners are doing.

I have not pulled it apart, but could it be the element, or elements, or if all of them are doing it. Does the stove has some sort of central voltage/heat regulator?