Two problems related to front suspension lower ball joint have been reported for the 1999 Ford Taurus. The most recently reported issues are listed below.
Lower ball joints loose and need to be replaced.
Total failure of the driver's side lower ball joint. 1999 Taurus with 58,000 miles. The ball joint separated and left me without any steering. I had just left the highway 5 minutes prior. There was no vibration or handling difficulties to warn of the problem.