Ah yes. You have yet to explain your reasoning behind this. I don't really see Ti in her. Te seems like the "last resort" for her so to speak. Do I see her analyzing the situations (Ti) at hand? No. I just can't peg her as one. So far, Nancy/Esteban's relationship (as of S04E10) seems to be very polar (ENTJ/ISFP) where they both understand each other in a weird way.
As for Shane. I'm sticking to eNFP. The way he stands up for what he believes in (Fi) makes me think he's an eNFP. His crazy ideas make me think (Ne) as well as the way he had talked to his father (or "spirit") in the third season. He wasn't too extraverted in the first couple of seasons, but then as the seasons progressed I changed my mind about him not being extraverted, which is why I am sticking to eNFP.
ISTP is what I thought too. Very I, very T, and very P. S enough not to really think otherwise. And if you think the temperaments thing holds water, I'm not sure how she could be anything but an SP. In one of the last episodes I watched she answered a question about what she's afraid of: "Calm." FJ? Really?
The one who buggers a fire burns his penis
-anonymous graffiti in the basilica at Pompeii