2000 Pontiac Grand Prix starts then dies

Computer problem
2000 Pontiac Grand Prix 6 cyl Automatic 74000 miles

We have a 2000 Pontiac Grand Prix GTP Daytona 500 special edition
its a great car and we love it we've never had any problems until recently
on new years eve we were dropping a movie off and the car was perfectly fine. We went in and locked the door on the car too many times. When we came back out it would start and then die quickly. We think it has to do with the anti theft part of the alarm. It seems as if its just cutting the gas supply off. Any ideas?
we've tried reseting the key
we've tried holding the gas pedal
we've check the fuel pump
disconnected the battery
disconnected all wires and reconnected and it still starts and then dies right away.
weve also tried to reset the alarm with everything that the book says and still nothing
and the last thing we tried we read on the internet to start it and let it die then leave the key in for 10 mins and do that 3 times. And it still wont work.
also when it starts it starts perfectly and sounds great
so any ideas?
thanks