Lose Power Steering problems of the 2004 Ford Escape

On two separate occasions while driving no more than 30 mph on city streets, I have lost power steering on my 2004 Ford Escape XLT. The first time this happened was 8/11/05 while I was 207 miles away from home on vacation. I made a right hand turn after stopping at a traffic light and all of a sudden I lost power steering. It was very hard to steer, but I managed to ease to the right hand lane. Fortunately, no one was behind me. Once to the side of the street, I placed car in park and started trying to turn the steering left & right until I felt the power steering return. I stopped at a Ford dealership to check the vehicle before the trip home. Dealer only looked under hood to check fluid and look for any obvious problem. No problem was found, and we made it home safely. The second occurrence was 9/6/05, same situation. I lost power steering after making a right hand turn after stopping at a stop sign. I managed to move to the side of street again, placed car in park, tried turning steering wheel until I felt power steering return. Drove to local dealership where they once again found no problem after checking wiring, pressure pump, power steering rack, & module. Nothing was replaced. I voiced my concern to service advisor that this was 2nd occasion and fortunately I wasn't on freeway or no one was behind me these two times. On both occasions I had my children in the car. We may not be so lucky the next time. I also asked service advisor about just replacing parts since can't find a problem, and he advised Ford doesn't allow them to do that since they didn't find a problem. This is the 2nd Ford/Mercury vehicle that has caused me nothing but problems, and I do not feel that we are safe in this vehicle.