My gf'* 04 GP (3800 S3 non SC) won't stay running when she starts it unless she pushes the gas pedal the instant it starts. It always does this. Cranks over and starts fine, then dies after less than a second of running. Hit the gas the instant it starts and it'll rev up and run just peachy.
It started off as a once in a while thing. Now it'* constant. Cold or not.
You can test the MAF by unplugging it. The car might stumble a bit at first but then run right. You will get a check engine light. Check the tech info area, there are tests there. If you have problems finding them or following them, just let us know.