I noticed a loud whistling noise coming from my car last week. We believe it is a pulley going out but not sure which one. The same day that happened my check engine light came on and I had it checked and they said it's an 02 sensor and a vacuum leak somewhere. Now the car is idling kinda high and sputters when I come to a stop. I feel like its going to die on me when I stop. It's a 2014 Chevy Cruze LTZ. Any suggestions on what I can check before buying all those parts?