Same car, the 2002 Mercury sable. It ended up being the starter like yall said.

If your banging on the starter, you realize the starter is bad. You can't depend it will keep starting. You're answering your own question by saying it gets harder and harder to start. You're lucky it is still working at all. Hope you carry food and warm clothing when you get stuck out in the cold. PARK THE CAR OR GET A STARTER FROM SOMEPLACE ELSE! Procrastination

That was over a week ago when i told you how to get it started. That was so you could take to a shop to get it FIXED, like i stated. That was not the soultion to the problem. Have the starter replaced before you have to get it towed! That will cost you even more than the starter and installation! Then you still have to replace the starter, or just catch a ride with somebody.