Fuel Pressure Regulator or Fuel Pump?

Hyundai Elantra 97 with 138,000 miles on it.. will start and run as long as I don't give it gas.. if I give it gas it will try to pick up rpm's but normally it shuts down. So I'm thinking it's the fuel pressure regulator or the fuel pump. I have changed the fuel filter so that's not it.. I will have to fix the exhaust manifold too..but I'm thinking that's it? what are you thoughts?? by the way....if I put it in drive... and give it gas ... it will not allow me to give it gas without it cutting out..

replace them both.