Fuel System Questions

I'm hoping since the Blazers and Bravadas are very similar that someone will be able to help me out. Our 97 Bravada has been running very erratically over the last several months, idling rough and stalling mostly also hard to start sometimes. We've had it scanned quite a few times and a variety of things seem to come up at different times. At this point all 3 oxygen sensors, the MAF, the plugs and wires, rotor and various small filters and or sensors have all been replaced. I've heard from a couple of people that it is probably the fuel pressure regulator; however, in searching online and looking in service manual we have we cannot seem to find out where that part is located on the car. I've seen pictures/diagrams of the fuel system at several sites but there seems to be a couple of different kinds. Any help would be greatly appreciated as I am at the end of my rope with this thing. :( Feel free to post here or email me. Thanks

1996-1999 4.3l Chevrolet/GMC models are equipped with the Central Sequential Fuel Injection (CSFI) system. The fuel pressure regulator is under the upper intake manifold assembly.