Chocolate Fever by Robert Kimmel Smith

Henry Green is a boy who loves chocolate. He likes it bitter, sweet, dark, light, and daily; for breakfast, lunch, dinner, and snacks; in cakes, candy bars, milk, and every other form you can possibly imagine. Henry probably loves chocolate more than any boy in the history of the world. One day-it starts off like any other day-Henry finds that strange things are happening to him. First he makes medical history with the only case of Chocolate Fever ever. Then he finds himself caught up in a wild and hilarious chase, climaxed by a very unusual hijacking!