you have a pressure valve on the fuel rail,push it in to let the air out of the gas line or your fuel filter could be stoped up.cars today do not vapor lock,it used to be you could pour cold water on the fuel pump,but this was befor the electric fuel pump.
I have to second the comment stating that new vehicles do not vapor lock. Fuel injection systems use a fuel vapor recirculation system combined with a venting gas cap that make vapor lock almost impossible. I would make sure you are using the right gas cap (I am pretty sure only one was offered). Other than that, we need more information on your problem to help you.
Search Ford Mustang Questions
Ford Mustang Experts