x2 as Brad said, start ruling out the components.
Do you have any check engine codes? That's a great start. If you don't have a scan tool, you can use a paperclip to jump 2 connectors at the ALDL, I forgot which ones, but you can find out in the forum, just search for it. If you have stored codes, post back and I can get you a flow chart for that code.
If you don't have any codes, start disconnecting things one by one, then re-connecting them. Look for a symptom other than what you are getting. If you unplug the crank sensor and you get cranking, but no start, that's not the problem.
Also know that some components are not required to be connected to have the engine running.
After I re-read your post, I am thinking it has more to do with the fuel pump relay / oil pressure sensor. The way the relay is designed is to offer you two seconds of fuel pump operation as you cycle the ignition key. That'll build up enough pressure to start the car. As soon at the car starts though, the oil pressure sensor then feeds power to the fuel pump. If there is inadequate oil pressure, or the sensor is bad, or there is a short, you may get the symptom of enough fuel in the rail to start the car, but not enough to keep it running.
Under the air intake is a fuel pump override connector (loose). Hotwire a FUSED cable between the battery positive and that connector. You will hear the fuel pump "whine". See if the car runs for more than 2 seconds. If it does keep running, shut it off because you may have low oil pressure and we would not like to hurt anything.
Post back and let us know.
