Try checking your FITV valve.

Take off your intake so you can see in your throttle body. Start your car and let it get up to operating temp. There is a hole inside of the throttle body. Once the car is at operating temp, put your finger on the hole. There shouldn't be any suction. If there is, you need to fix your FITV.

To fix the FITV, you need to take it apart and screw the plunger back in (really easy).

You should also check for vacuum leaks in your intake system.