One problem related to ball joint has been reported for the 1999 Toyota 4Runner. The most recently reported issues are listed below.
The ball joint on my 1999 Toyota 4runner broke while I was driving the vehicle. By the grace of god, I stopped at mcdonald's before my long journey onto the freeway, with my 9 month old baby in the car, and that saved us from a very bad crash that may have taken our lives had we been going 60-70 mph. How does a ball joint break in half???.