I have a 94 Toyota Corolla

I have a 94 Toyota Corolla. I now have problems with it stalling every 5 minutes or so. It will start right back up if I park it and turn it off. Just have to pump the gas a little to get it going. I recently got an oil change thinking that was the problem but it still does it, The guy told me my air filter and fuel filter needs changed. But now my step dad is telling me it could be the fuel pump. I just want to know what exactly could make it stall out like that out of nowhere while im driving. I just dont want to spend money on a part I dont actually need. I will change the air filter because I know it needs it, but is that what is causing the problem? The man also tested the battery, transmition and said it was all fine. So I have no clue what could be the problem. I need help please!