[shorod]

There are a few ideas that come to mind. When you tried to start it and nothing happened, did you happen to notice if any of the lights on the dash came on? If not, it definitely sounds like a power issues. Certainly start by checking the connections at the battery making sure they are clean and tight. Also, make sure the battery cables are in good condition.

How old is the battery? It's not unheard of for a battery to have a broken internal connection. After some bouncing around or heat the broken connection may go open circuit. If the batteries 4 or 5 years old or more, you might just replace it since it's near the end of its useful life anyway. If it's newer, you'll want to verify that is the problem and try to get the battery pro-rated under warranty.

Several other Taurus owner's have experienced problems with the Transmission Range Sensor (TRS) which can cause all sorts of odd electrical issues. That item would be obviously correlate to the odd issue with the symptoms changing when you move the shift lever. You can search the forum for "TRS" and/or "safety switch" (aka park/neutral safety switch) to read up on other experiences with the TRS.

If you have a spare key for the car, you might try that and see if it works a bit more reliably.

-Rod