Just wondered if the engine turns over at all. I had a problem with my 1999 cougar that was similar. The problem started small, just stalling every now and then after starting it. It progressed to the point where in order to get it home from work one day, I had to start it in neutral with my foot on the gas and give it he** when I slid it in to drive. It was really lots of fun because every time I braked it stalled, so I had to do that all the way home.
It ended up being the air control valve. We replaced it first with an after market valve from auto zone. It ran perfect, but made a horrible whirring noise. We returned that one and got the correct one from the Ford Garage. Everything works great now. The part was about $60 and was easy to install.
Let me know if that helps.