Car has trouble starting

I have a 1997 Ford Taurus LX v6 DOHC. The car has almost 150000 miles. After driving the car for about 30 - 45 mins, I turn it off. About 20 mins later, I go to turn on the car and it has trouble starting and stay running. I turn the key to start it and it begins to sputter and then cuts off. When this happens, the RPM goes up and down and never gets to 700 - 800 RPM. After waiting for about 10 mins, the car finally starts but I have to push on the gas pedal to get it started and kept running. Once started, it runs fine. The car has enough gas, the fuel pump kicks on, and the oil level is full. What could cause this to happen?

You will need to have the fuel pressure checked first. Also, cam sensors seem very heat sensitive and fail with the symptoms you describe.