Help me AEU86, you're my only hope

[totta Crolla]

Probably worth checking that your O2 sensor is telling you the truth. It should be showing somewhere between 0 - 1v on your meter. To give a stable output an un-heated sensor relies on high exhaust temperatures and this is typically achieved when the engine is under load. I use a narrowband sensor to feed back to my ecu and a wideband to tune. With both sensors fitted it became obvious that the un-heated narrowband sensor was sending rubbish until it got really hot. Fitting a heated sensor cured this.