[Coffee.]

I'm guessing the caffeine is making a difference, since Mountain Dew is a high caffeinated soda and you may be hooked to the caffeine. You could try switching to coffee or tea.
And said comments are right. Soda is terrible for you. I doubt kidney stones will be something in the close future, but soda is horrible for your teeth, my teeth have a soft enamel because of my energy drink/Dr. Pepper addiction. Hence, I now mainly drink coffee.
Mountain Dew is not physically addictive, so I wouldn't worry about it from an addict's point of view, however, you have stolen from your parents. I would recommend switching to a lower sugar, caffeinated alternative, and go from there.
PM me if you need any more advice.