1998 Ford Taurus Transmission Disengages

Whenever my daughter brings her 1998 Ford Taurus (120,000 miles) to a complete stop the automatic trnsmission seems to ‘slip’ out of gear. It can be easily re-engaged by shifting into neutral or park and back into drive. The transmission fluid is full, looks and smells good. The mechanical linkage in the engine compartment also appears to be is working correctly. Any ideas??

Have a transmission technician check the line pressure in D and R at idle and then again at stall. That should show any problems with the pump and idle pressure. If the ‘neutraling’ problem is not seen in the shop, the line pressure should be monitored to see what happens when the problem occurs. A little more diagnosis is needed.