Greetings;

Although it may be a sign of an internal hydraulic leak or valve body fault in the transmission itself, it could also be a symptom of a broken engine mount.

Tauruses commonly experience engine mount breakage; especially of the silicone filled mount on the right side of the vehicle near the firewall. If you have a broken engine mount (or more than one) that is allowing the drivetrain to shift position with acceleration and deceleration, it could pull on the shift linkage and cause teh transmission to actually shift gears when stopping. Another sign of an engine mount failure would be any unexplained bumping or thunking noise when starting or stopping.

I would suggest taking this particular problem in to a repair technician for diagnosis; diagnosis will probably be pretty inexpensive, as there likely will not be much billable labor time involved in checking the vehicle. If you do have a broken engine mount, this is a potential safety issue that you will want to have corrected. If the engine is moving enough to shift gears, it could also possible do the same thing wthe throttle linkage resulting in vehicle control problems.

I hope this is helpful; if so, an accept would be most appreciated! thanks!