[shorod]

There are a few items that come to mind. Starting with common issues, the ignition switch has been a common failure point across several models of Fords, and the Transmission Range Sensor (aka Park/Neutral safety switch) have been common problems on the Taurus. Either of these have the potential to cause the symptoms you described.

The Crankshaft Position Sensor (CKP) on a Ford of that vintage will also cause the engine to shut off in the event of the crank signal disappearing. If you have an oil leak near the crankshaft pulley, or worse, a coolant leak, fixing the leak and replacing the CKP would be high on the list of suspects as well.

You could shotgun all of these and see if that takes care of the issue. There may be a recall on the ignition switch, worth checking. Or, if you don't want to replace something that's not the problem, you could do a quick little test next time the car stalls. I assume when this happens you shift to neutral while the car is still moving and try to start the engine back up. If that doesn't work for you, try bringing the car to a complete stop, shift to park, and see if it starts up reliably that way.

There's a less likely chance that the battery has a bad connection internally that randomly opens up. Assuming the alternator is working though, I would not expect this to cause the car to die without at least providing some other indication.

-Rod