I have a 1999 Gt and for about a week, when I first would start my car in the morning the rpm's would drop real low as if the engine were going to die and I would have to rev the engine to keep it going. It would start fine for the rest of the day, the first start was the only problem. Now today, it wouldn't quite get started before dying. With each try it got weaker and weaker. Any ideas on what this could be, I assume it has something to do with the fuel system.

 

IAC valve. Clean it out with some brake/carb clean and dry it out good. That should get it to work for a little bit. I would suggest replacing it soon, though. It's about $75 from Ford and cheaper at AutoZone.