On the top of my fuel return line, on the fuel rail, is a vacuum line... where does this line plug into?

 

I know that it ends up there... but i was reading a diagram that shows the fuel pressure regulator vacuumed into the FPR control solenoid valve and than into the manifold.. so I guess the question is Do I need the control valve or can i just run it into the manifold and have it be fine? Also when I plug it into the manifold my car idles @ 500 and wants to bog out n die.. do you think its a bad FPR?