Car won't stay running

Cant believe im answering a question when my grand am is still down, but as to your car dying right after you start it, I believe that the pcm may be disabling your fuel injectors (gm's passlock protection working overtime once again) Anyway, first, check to see if your theft deterent light is lit or flashing on your instrument panel when you try to start it? If it is, the problem according to the book is that your pcm has detected what it believes to be an attempted theft of your vehicle, this can be caused by several different reasons. My suggestion would be to attempt to start your car and when it dies, hopefully you see the theft light blinking, don't touch anything! Leave the ignition switch in the on position for 11 minutes and the theft light should go out which will mean the system has reset. Then attempt to start your car again. If it doesn't solve the problem you might try disconnecting the negative battery terminal for about 10 minutes, reconnecting with the ignition switch turned off and again follow this procedure. If your theft light was not blinking but stays on solid, then your in the same boat as I am meaning we're screwed! Ha!Ha! My GA is a 97' GT 3.1, According to the book a solid light is caused by the absence of a password to the pcm from the ignition switch 3 times when attempting to start the car (I had my ignition replaced by the dealer and it supposedly programmed to the car $300), "or" encountering a bad timing cycle (if I continually attempt to start it, eventually the pcm will fail to disable the injectors and the car will run, However all warning lights on the cluster remain lit and tach does not function, in other words the only thing working on the cluster would be the speedometer and possibly the fuel gauge, I already replaced the cluster, next thing I replace is going to be the internal wiring harness and the pcm itself unless I get a suggestion here). Anyway, hopefully I at least helped with your problem and possibly someone can assist with mine. Good Luck to you but remember, "Buy a pontiac once shame on them! Buy one twice shame on you!"