One problem related to power assist brake vacuum has been reported for the 1997 Ford Mustang. The most recently reported issues are listed below.
Power steering/brake booster hose replaced, now strong vibration in brake pedal and at brake booster, and loud audible hum, no noise/vibration prior to replacement, dealer says new line different than original but is only replacment and can do nothing further - I'm concerned that vibration may cause brake failure since power steering shares pump with brake booster.