I got a 2003 Grand Prix Pontiac 3.1 I just put a fuel pump and fuel filter on my car and its not getting gas and I have to keep my feet on the gas pedal to start up.

reinspect your doings, verify the parts run and are delivering fuel. Listen, operate the ignition switch, wait, listen, crank engine, listen. does the pump run 1&1/2 sec stop. then run when cranking ? can you get the correct gauge and measure high pressure fuel? verify the injector operation? If not go get pro help. It takes some experience to verify correct operation for someone to help. There are many (if/thens) about to guide the diagnosis. An automotive database is available for free at the public library. Some part stores can assist with questions or suggestions. A technician normally has not only test equipment, but experience and known good substitution parts. You can rent or borrow testers with a credit card, learn, borrow, return at many parts stores. Return here if you need to to update what you have and get ideas too. You do not have a starts but dies situation ? like an antitheft shuts it off ? after it starts.