I stand corrected. The coolant sensor sends the signal to the electronic control unit on this engine. There, it is split into sending the information to the gauge and the fuel calculation.
If the Coolant sensor is good, the rectification is puzzling.
This is the list of the areas to investigate right out of the book:
Air induction system
Mass air flow meter
Engine coolant temp. sensor
Gas leak on exhaust system
Heated oxygen sensor (bank 1, 2 sensor 2)
You have replaced the MAF, the First exhaust sensor in the system and the coolant sensor.
The questions that remain are these:
Intake manifod gaskets (might be worth investigating)
Fuel pressure (I would not think this is your issue)
Injectors (SOme really good fuel injector cleaner would be recommended; use us a great product called BG 44-K
Possible exhaust leaks. (you did not mention this, so I would think there is none.)
At this point, I would add a can of BG 44-K to the tank and driver it, running the fuel down as quick as possible, then repeat. Clear the code and drive it, see if the code comes back. If that does not provide any joy, I would be looking at replacement of the intake manifold gaskets.