It doesn't surprise me that the PC III connects something to the 02 Sensor. Once the engine is at operating temp, that is the sensor where the PCM gets its main signal with lesser inputs from the throttle position sensor as to amount of fuel to add.
If you are going to take the 02 Sensors out of the mix then you'll have to provide an artificial voltage reading to the PCM when it is in closed loop mode, which is just about everything up to 3/4 throttle.
1971 R50/5 Cafe Project
2013 DL650 Adv