unstable idel problem

hey guys recently been noticing problems on my b18. the idel seams to be unstable. it seams the be unstable i mean it seams like it is gonna stall then it shoots up to 1000. the engine light comes on once and a while and the code seams to be the o2 sensor. could the sensor be causing that. also it happens even when the engine light is off.
thnaks for any help

it could be your o2 sensor.

but some easy fixes are
1.check for vacuum leaks
2.unplug your iacv, if it fixes your idle then take off you iacv and clean it, if you put it back on and still has bad idle then the sensor is bad. clean it with carb cleaner, there will be alitle screen. youll see it.
3. take off FITV sensor and screw it all the way in

that should fix your idle, if not then it didnt cost you anything. and then if that didnt work them maybe its your o2 needing replacing

what is the iacv and the FITV and where are they.
thanks for your help

iacv is on the back of the intake manifold and the fitv if your car has one, is under the tb