I had the same problem when I first started. I was so used to drinking Mt Dew. My consultant said to cut back in one week, but it didn't work. I started cutting back very slowly over the course of two weeks and it definately helped.
Definitely not! I never did quit all the way. But I find that the more water I drink in the morning the better I feel. Makes me think that some of the time when I felt I needed the caffeine I actually needed real hydration.