Yeah... no factory sensor means that the car has no clue about what's happening in the combustion chambers. The ECU needs to know what's happening as it's using this data to make corrections to get close to its target A/F. Put the stock sensor in and get a second dedicated bung for the wideband sensor. For all you know, you could be running lean like hell and it can damage an engine real fast.

Idle at 1400 is way too high... fix the sensor first and see what happens.