While the fuel pressure is being checked, check it with the vacuum line pulled off from the fuel pressure regulator and see if the pressure rises. After shutting the car off, check for any fuel or fuel smell in that vacuum line.
Besides that, with the symptoms that you have, I'd be leaning toward what was suggested above...a bad MAF. The diagnostic steps say to do as you have and disconnect it and check how it runs. My experience has been that it was not a useful check. However, as it is not an inexpensive part, make sure other things are ruled lout first.
Black 2000 SSEi, Silverstar Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, drilled 180 degree thermostat, Intense FWI, PCM, shift kit, and 3.4 Pulley. Solid front mount.