Monument Valley Sighting, Arizona - 1991

Saucer shaped - silver in color. About 1 to 2 miles over desert South of highway 160 we were traveling southwest bound on towards Flagstaff. Hovering but not moving about 500 - 1000 feet above the base of a small mountain range. After about 10 seconds of hovering stationary above mountain range, object then moved down the slope of the mountain range a bit, still hovering until it was about 200 feet off the ground (very close to the ground), North/Northeast bound off the base of the range at this point. Object slowly accelerated northeast-bound for a few seconds guesstimating between 50 and 100 mph, still about 200 feet above the ground, afterwards it then shot at a tremendous speed northbound, so fast I could just see it dart outside of my peripherial vision.
 I didn't realize what I was looking at until it moved from it's stationary position above the mountain, at which point I was a bit in shock when I saw the object fly downwards then hover along the ground moving. When it was moving northeast about 50 - 100 mph is when I think I realized what I was looking, and yelled in our car "Hey do you see that?!". My family members lazily asked me "See what?". By that time it was gone and to this day irritated that no-one else saw it.
 There were no lights on the object, I heard no sound (being inside the car I didn't really expect too). The car ran fine during the entire event.
 Don't know what it was. I'm not a believer in little green men. I was about 14 years old at the time coming back from a trip to Colorado. To this day I don't know what it was, but I am 100% positive I wasn't halucinating - I was awake and alert looking at scenery. It could have been an expiremental military aircraft for I'll I know, but I have never seen anything manuvere they way that thing did. It's the only sighting I have ever had of anything fitting the category of "UFO".
Witness indicates that the date of the incident is approximate.  PD