95 for Aerostar

I have a 95 ford aerostar 105000 miles. Recently I have noticed that at about 45 miles an hour there is a moderately loud humming or vibration sound that only stops when I press thte brake pedal. I have asked many people and they are not ure as to what it is. I have also noticed that when I slow down and press the brake pedal the steering wheel turns back and forth on its own, but just berely. Please help if you can