I had that problem. As it turned out I needed a rear brake job, as the indicator was rubbing against the rotor making an annoying sound that I went to the dealership to address. My service advisor was saying that most of the Escalade's he sees have problems with the rear discs and that sometimes the emergency brake doesn't fully disengage which causes premature wear.
I took mine in to be looked at, they wouldn't touch it because I upgraded to 14" rotors, however they found that one of my rotors was hanging!! Good thing I took it in... I still get the problem of my foot going to the floor.
When I turn the wheel all the way to the left, the brake tightens up more than usual and you can stop. But with the wheels turned all the way to the right, the brakes go out and your foot goes to the floor and it slowly, slowly slows down. A few members suggested that I switch out the brake lines for metal rather than plastic.