I think I'm both extremely E and extremely I.
I get LOTS of energy from social interaction, new experiences, the outside world, etc. I also hate being cooped up, I can't stand sitting around doing mindless work unless I have someone interesting to pass the time with.
But I get just as MUCH energy thinking and imagining - playing with scenarios in my mind, inventing music/images/"movies" in my mind - rather, continuously developing them in my mind. If I'm allowed some time to myself to mindplay, it's revitalizing.
I also tend to focus very narrow and deep, rather than "expansive and light" like an extrovert's said to. When I have a mission in life, my life is my mission. It becomes obsession. This usually manifests in my business/financial goals, but also certain hobbies.
Is it possible that I'm an ISTP?