[YOUTUBE=http://www.youtube.com/watch?v=cXw4Rw6xXxU&feature=related]star wars: clone wars chapter 11[/YOUTUBE]
In this videos, you can see that act before reflect from the impulse of an affective pulsion is the natural way to Anakin. An ISFJ? Absolutely not, Anakin is unable to stay concentrate on details and explanations and to respect any rules. Si is the inferior function of Anakin, he can't accept the realty, notably that he can't forgot the rules to do everything it seems good to him in the galaxy, and that he could never be enough powerfull to save everybody. His principal motivation is to challenge this natural weakness, that lead him in the seeking of more and more power and next in the falling to the Darkside. The novelisations reveals that Anakin is definitely an extroverted intuitive.
He's F, he's very expressing about his feelings, notably is the first episode and with padme, but as jedi, he can't express them, because he could be hunted from the jedi order for. Actually, Anakin have many times think about leave it, but was deterred by padme, his INFJ mirror.
So, Anakin is definitely an ENFP.