I managed to quit caffeine by switching to 2 decent dehydrated coffees, one decaf. That lets you smoothly titrate it down to full decaf, with the aim of being somewhat tired with a very mild, tylenol manageable headache some of the day. After a few weeks of that, I was pretty much off completely.

Now I can drink a single soda or coffee and stay completely alert while night driving! It's great. A day later I do get extremely sleepy, but not sick or headachy.