1993 Pontiac Grand Am Fuel Pump/Filter

I have a 1993 Pontiac Grandam V6. It was imounded for 30 days. When I took it out it started dying when I would brake at a red lightor slowed down after driving more than 5-10 minutes. It runs fine sometimes. I've been told that it could be the fuel pump and or the fuel filter. I also was told it is due to the car sitting idle for so long with out being driven. Can you please help and lead me in the right direction.