WHITEPRINCESS : just my opinion, probably ur mechanic knows the problem, but said O2 was faulty so he charged u more, and fixed the lil problem caused ur rough idle.
Rough idle could be lots of things,
Dirty Air Filter, AFM Conection?, or Spark Plug etc,
Clean them and see what happen?
To reset eCU...Instructions:
- FUSE box driver side kick panel, (remove it)
- look under, u should see a grey plug,
- there should be 2 wires on its own,
- short circuit it for 2 second,
ecu should be reset, check for engine light flash.
Hope it helps,
cheers,
darrien