In your first thread on this subject you stated that historical codes were present but Dave just reset it.
Do you know what those code/s were??
The "usual" sensor to give problems around this age is the A/F sensor in the manifold (and it's usually the heater circuit that does down).
You also have an EGT sensor in the up-pipe (unless the up-pipe fitted has been decatted).
Both these sensors have plugs near the boost solenoid on the drivers side.
Can you confirm you actually unplugged the A/F sensor (4 pin plug)?? and not the EGT (2 pin plug)
Still somewhat confused, as you state code readers find no codes and the CEL is not lit, what are you trying to fix??
Until the CEL actually comes on and stays on, you won't find any codes especially as the ECU has recently been reset and all codes,including historical, cleared.