You will need to check for codes anyway. Hows your cold starts? Does your car stays on or do you have to crank it a few more times to keep it up? If cold starts are good, your O2 sensor is fine.
It could be:
1. Idle Speed Sensor
2. MAF
3. O2 sensor
4. A leak
5. MAF flow interruption.
6. Too much fuel flow/pressure.
It could be:
1. Idle Speed Sensor
2. MAF
3. O2 sensor
4. A leak
5. MAF flow interruption.
6. Too much fuel flow/pressure.