One problem related to transmission not engage has been reported for the 2001 Mercury Sable. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Mercury Sable based on all problems reported for the 2001 Sable.
The transmission would lock in park and disengage at 40k, a sensor was replaced. Then at 49k the transmission blew while driving (internal). Poor transmission engineering. I'll never buy another Ford/Mercury.