Here is some possibly bad advice from someone who was once in a boat a little like yours and has just gotten accepted to a couple of very cool interdisciplinary programs where you can do stuff a bit like what you are saying. But the road between A and B is not necessarily easy.
The first thing is: don't try to reinvent the wheel (this is a bit what your post sounds like). Everyone already knows about Foucault, you can use him to think about institutions, the formation of subjects, blah blah blah. Do not think of yourself as a "Fouauldian" or an exegete or else you will not get where you are trying to go. Take a step back and ask, "Why I am interested in MF in the first place? What questions lead me to want to think about MF?" Basically you need to decenter Foucault from your idea of what your intellectual project is if you want to do something other than disciplinary work (if you want to go into English lit, for example, it might be fine to be that into Foucault - but then you are just an epigone)
My suggestion is to plan to spend some time away from the academy for a couple years supporting yourself in other ways and reading as many books as possible. You still have an enormous amount to learn and all it takes is time (you don't need a professor to tell you, just go read all the stuff you know you haven't read). You may find that during this time, and in the bubble-bursting experience of no longer being in a formal educational environment, your idea of what you are interested in will change and become more refined.
I spent two years outside the academy, and I'm now finishing up an MA in English which I found deeply unsatisfying but which helped me understand what it is that I DO want to do. It's only now, four years after my BA, that I'm really even qualified to begin doing the kind of interdisciplinary work that you seem to want to do. And it's now finally paying off, but only after a period of four years which was not especially emotionally easy.
I would take some time off, find yourself a bit and read for several hours every day, apply to a disciplinary PhD program in English or Philosophy (make sure you get funding), and then bail with the MA and apply to an interdisciplinary program. Some good candidates might be UC Santa Cruz History of Consciousness, U Minnesota Discourse and Society, , Berkeley Rhetoric. You could also apply to these programs right out of BA but probably much harder to get into.
basically, don't be in a hurry. you can't do what you are saying you want to do if you are in a hurry.
good luck