Our 1998 Taurus slips out of Drive occasionally when stopped at a stoplight. It is an automatic, and we shift it into Park,then back into Drive, and it will go again. This is intermittant so far. Is the transmission kaput? Any other things to check out?
Have you properly checked your transmission fluid level?
Could be a transmission range sensor issue, too - those were far more common than actual transmission failures on the Gen III Tauruses, and FAR, FAR, FAR cheaper, too…
We had the transmission fluid and filter changed in May; it seemed to help a little for a while.
We’ve run into quite a few Tauruses & Sables at our shop with worn shifter links that connect to the shift cable on top of the transmission. There’s a plastic grommet that wears out. This might just be your problem.