I have a 2000 Malibu with the 3100 v6 in it and its giving me troubles.. Please help

I know its not an impala but I follow this forum and there are alot of knowledgable people on this one..
So heres the problem:
when you start it, it will run for 5-7 seconds then shut off... try to start it again samethings happens after 5-7 seconds... It has fuel pressure... but the gas gauge shows empty and the low fuel light is on BUT there is several gallons in the tanks... I just put them in... After about 3 times of trying to start it the anti theft light comes on and stays on... Can someone please help... thank you in advance... just suggestions would be good