2000 Windstar won't start

My wife called me from Walmart tonight because the van wouldn't start. It was turning over just fine, but made no attempt to start. Fuel pump shut-off was fine, and I tried the spare key with no luck. I noticed that the THEFT light was flashing when we turned the ignition on, so I disconnected the negative battery cable for a little while (while I was checking fuses) and after hooking it back up it worked fine. Now back up a few weeks ago....we had a week or two of the battery dying, but it and the charging system tested fine. I figured it was either the great big pile of corrosion on the battery terminal or the remote-start system, so I disconnected the remote start and cleaned the battery. Everything has been fine for about two weeks. Now my question is this...is this latest thing with the PATS just a fluke, or does it mean something?

Have your battery "LOAD" tested.

The battery has already been load tested.....it was fine.

How old is the Battery?

I don't remember exactly, but I know its at least a few, if not 4 or 5 years old. My wife tried to start it again this morning, and the THEFT light was flashing and it wouldn't start again. She said it was turning over fine again, but when I went out and tried the THEFT light wasn't flashing but the engine wouldn't turn over. Used the jump starter on it and it started fine. It does seem like the battery is dying quicker than it should. Could the battery really be causing the PATS problem even though it tested OK twice? I've gotta drive it 25 miles or so this morning.....I'll check the voltage after I arrive to see what it charged to.

The thief light blinking unuallly indicates low voltage. To simplify things, just change your battery. You need one soon anyway.

Ok, I know when I'm whipped. You two were right. I had my battery tested (for a 3rd time) at a different place and it tested bad (wasn't holding a charge). I wish Advance Auto would have found that 2 weeks ago.....would have saved me a lot of time. The good news is it's 5 years into the 8 year warranty, so I not only get $30 credit, they sold me the new one for the same price I paid 5 years ago, so I saved another $25. Thanks for the help.