One problem related to rearview mirror has been reported for the 1999 Ford Explorer. The most recently reported issues are listed below.
The rear view mirror vibrates excessively. I have been to the dealer to address this problem and am currently on my third rear view mirror assembly, and the problem still exists. This is the upgraded auto-dimming mirror. The vibration gets so bad that I can't see any details out of it, and prolonged driving results in headaches. The problem exists at speeds above 25 mph.