One problem related to differential unit has been reported for the 1999 Acura TL. The most recently reported issues are listed below.
Transmission surge, increase in speed when stepping on accelerator. Slammed into gear, mostly when the engine was cold, and at a stand still, and then surged into gear. Took vehicle to dealership and it was under recall. The dealer refused to fix it. Consumer will contact the manufacturer. The differential gear wobbled. Which caused the axle seal to break. The transmission fluid leak out from the axle casing. The dealer simply revealed a broken gasket seal, a defective axle and not the real cause of the problem (differential wobbling).