2000 Daewoo Lanos intermittently idles rough

timing may be off, the belt for the engine may be lose and need replaced, or you have a vacuum leak.

You need to replace the IDLE CONTROL VALVE as it gets blocked.Try just tapping it with a bit of wood ,to see if it raises the idle speed..Sometimes just this works.

have you tried using normal gas???(using ethanol,if the car is not designed for it, will cause rough running/damage.

Knock Sensor - is not an issue
O2 Sensor-just sees the condition of exhaust, during the stall & sets a code

I would look at the Idle Speed Motor, TPS Sensor,even vacuum leaks,Egr Valve.
Don't know your veh systems, Hope that helps some.

is your engine light on?

If your car is running rough and it's fuel injected (which yours is). Follow the air intake (black plastic box - housing the air filter that has tubing that goes to the motor) until it reaches the Throttle body (rounded metal air intake at the end of the plastic tube - has one large flap inside). You will want to remove the hose clamp and thoroughly clean the throttle body and the AIC (air idle control valve - small canister attached to the throttle body). Use off-the-shelf cleaner from any automotive store. This takes about 30mins to 1hr depending on your skill level. This will result in a cleaner smother idle and smoother performance. This is a common issue in today's cars. I have to do this once a yr to keep my modified car running happy.

Take a look at the later parts of this article for pictures to give you an idea:

http://forums.nicoclub.com/zerothread/319146

Good Luck

check fuel filter and check fuel for water or contaminents
then check fuel pressure with gauge also while driving
may have pin hole in leads - spray water with salt solution over HT leads while engine running and then rev to see or here spark jump(missfire)
recheck spark plugs - did you crack any on installation/removal/installation?
what are the codes and description if stored?
what is engine live data parameters like do they look normal (right specs for range/operation)?

there is a screw at the end of the throttle cable. get someone to rev the engine an your see it move.turn the screw anticlockwise and the idle should slow. clockwise will raise the idle speed.

IAC solenoid (Idle Air Control) is not working and remains closed .... air is passing thru the main air intake duct , opened by pedal ... and not by the air bleed conduct (must open while main must be closed .. Pedal Depressed.) Check IAC Solenoid and connectors. Replace if need....

Is the garage you took it to a daewoo dealership? If not then try one; they should be able to run a diagnostic. If so, take to a different one.

I would think it is the o2 sensor. If you disconnected it then it sounds like you have the knowledge to replace one. When mine went bad the car didn't stall.