Um, the coffee I drink has way more caffeine then Dew so if you're trying to cut out caffeine then you'll need to drop the coffee too. I did it a few years back and after about a week and a half of terrible headaches, I felt quite a bit better.
I'm thinking of trying to cut back on caffeine again too, but I really like my coffee and tea. I think I might start with tea to step down and then try and get to only weekend morning coffee instead of the multiple cups a day at work amount.