My car has started stalling right after starting up,it usually starts back up. on 2003 Buick Regal

i have tried the Chevron Techron Concentrate and it was better for a day and a half, but now it seems to stall out everytime i start it. is it the fuel pump? i had the fuel filter replaced last spring (2012). all other maintenance is up to date.

Asked by for the 2003 Buick Regal