1999 Escort ZX2 timing belts.

We had a belt go out at 77,000 mi. It was at freeway speeds and by the time we got off the freeway, the engine was shattered. I had it professionaly rebuilt, by a shop I had used numerous times over the years. After 20,000, miles there was belt trouble again, and the valve regulator ???, was fixed, by Ford, for $1700. 17,000 mi later, the belt idler bracket broke off, the front of the motor, $1300. Yesterday ( 12,600 mi.later) the belt popped off. I'm having it towed in today to analyze. This vehicle, since day one has been my wife's commuter. She goes 58 miles a day 5 days a week on the freeway. That's pretty much it. We live at 100 feet above sea level, and her job is at 1700 foot level. I had one guy tell me it was cause of the climb everyday. Also, this car has never idled smoothly. I was told that that was due to the dual overhead cam? I have stopped and asked other ZX2 owners, and they say the same thing. One lady said her husband was a mechanic at a Ford dealer, and he could not smooth out her ZX2?