How can I fix my 2000,Ford,Escort?

My 2000 Ford Escort started making a pulsating grinding sound when I apply the brakes, the ABS light has also been going on but not all the time, the shifter occasionally locks into park, forcing me to use the override to get the vehicle into my garage. So far I've checked the brake system calipers, rotors, and pads they are all fine. Next I figure it has to be the ABS Module so I replaced it (a bit costly if I may add) I thought my problems were resolved till I took it for a test ride and it did it again. Now I'm stuck I'm thinking maybe the master cylinder. I would appreciate your help in resolving this. It's driving me crazy.