Oh, but it's so much fun to stuff your face and get so much attention! This is what 2-1/2-year-olds do so wonderfully well. And he got the attention, so he'll think, "That was great! I'll do it again!" It's not so much a habit as a theatrical stunt.
Giving him one bite at a time may be time-consuming, but you might try it. However, you need to do it in such a way that your son doesn't get a rise out of you. Stay friendly, but say something like, "Oh, it's not good to eat more than one bite at a time, so I'll just give you this. When you want more, ask me." Then do what you usually do while he's eating. Try not to notice too much. If he doesn't ask for more, then he's not very hungry. Don't worry - he won't starve. You can give him a little extra at snack time if you think he needs it. But if he wants to stuff all the snack in his mouth, do the one-bite-at-a-time thing again. Be assured you won't be doing this forever... just until he gets the idea.
The idea, of course, is that he doesn't have an audience for this sort of show. A two-year-old's job description is to test the boundaries, and he likes feelings of power (who doesn't?). His food intake is something he has power over, so you need to pick your battles carefully. When the stuffed-face performer realizes the act isn't not so much fun when it doesn't get a rise out of Mama, he'll let it go. He may go find something else to try, but that's another matter!