1. What brand are the O2 sensors? The 3.4L has 1-wire (unheated) sensors, that can be very sensitive to operating temperature.
2. Why are you concerned about the 1.5 volt MAP reading? The intake manifold vacuum at idle averages 64.8 kPa (19.2"Hg), which is acceptable. You can calculate intake manifold vacuum by subtracting MAP (average = 39.6 kPA @ 1.55 volts) from BAROMETER (104.4 kPa). A bit high for barometer. What is the elevation above sea level where your friend lives?
3. What is the condition of the EVAP system - carbon canister in driver side rear fender to purge solenoid on engine)? Possible source of a vacuum leak.
4. PCM runs in speed-density. Critical inputs used to calculate mass air flow are RPM, MAP, IAT, and CLT. The readings from these sensors seems rational. For example at idle, RPM ranges from 710 - 904 RPM, MAP from 37.3 - 44.3 kPA (possibly indicates a rough idle/misfire), IAT 80 - 81degF, CLT steady at 215degF.
5. Were the changes you listed ("New o2s, tps, fuel pump, injectors") replaced in an attempt to solve the poor fuel economy? Did any of them make a significant difference? Have you checked the fuel pressure? Are the injectors a good quality part - there are some very inexpensive Chinese counterfeits that are terrible)?
So far, the thing that puzzles me is the fact the long term fuel trims (LTFT) seem to drift up and down at random. I'm looking for a correlation to something like duty cycle on the EVAP and EGR systems.