2000 Chevy Silverado Fuel pressure regulator

I replace fuel filter, dist. Cap and rotor and wires and plugs. When you start it up first thing in the morning it runs rough and wants to die. Let it set and run for about 5 to seven minutes it runs good and you can run to store and it starts up fine. If you let is set for about 5 hours it is hard to start again.
I think it is the fuel pressure requlator but I could not found it on the engine. Please tell me where it is locate at. Please.


It is a V-6 Vortec.