2000 Ford Explorer Grinding from front end after brake job

I recently changed out the front brake pads, and about a week after doing that, I've noticed a grinding noise coming from the front end. It's relative to my speed, and completely independent from the engine; the grinding is still there while coasting and remains the same if I throw it in neutral and rev it a bit. At higher speeds, the car seems to "float" away from me from time to time, mostly around curves at 60+ mph. Any ideas?