99 Grand Prix SE Stalling Problem

Hello, I have a 99 Grand Prix SE 3.1 engine with about 154,000 miles on it. The other day when I went to start it up, it would start and imediatly die, after trying to restart it a couple of times I was able to keep it running by hold my foot on the gas pedal and holing it at about 1500 rpms. If I wait 10 or 15 seconds I can let my foot off and it will idle and run with no problems at all, but as soon as I turn it off and try to restart, same thing happens, Done think it is the fuel pump beacuse it will run fine after get it running. It happend all of a sudden. One day it worked the next it didn't. Any ideas on what this could be would be very helpful.
Thanks in advance

It could be a number of things. Your best bet is to see about getting the codes that have been set. If nothing else it can help these experts that we have here help to narrow it down for you. It will also save you a lot of money changing out sensors till you find the one that is the cause.

I scanned it and got no errors....Any ideas???

it sounds like you have bad fuel pressure. i would check that first. the pressure on a 3.1 should be 41- 47 psi. after the motor is shut off, what does the fuel pressure hold at and for how long? it sounds like it could a fuel pump relay which go out mostly in the winter, and your symptoms are classic. if that is not it, try the maf sensor- just unplug it while the car is running and see what happens. another question is does the security light come on? could be security realted although it does not sound like it.