I've tested as both but I've noticed that in general, I act like more of an F than a T. For example, I'm as far from 'cool' as a person can be. My moods are up and down and I don't really seem laid back like the typical picture of an INTP. However, I'm naturally quite analytical person and seem to have more of the 'typical T interests' apart from math, which I hate with a passion.
I've read that it's harder to get a T to laugh (if this is true or not, I don't really know) but me, I seem to laugh at anything and everything. I do have quite extreme emotional reactions and 'lose my cool' quite a lot, which makes me think I'm more of an F but at the same time, I can just as easily get absorbed into some kind of intellectually stimulating task and hours can pass by before I realise I've missed dinner and it's the next morning!