I wanted to correct it because millions of folks are convinced that all cars have Idle Air Control Valves. They are a frequent problem on cars that have them.
On the HHR the computer controls the air flow by adjusting the throttle butterfly using data from the MAP, MAF and #1 O2 sensor.
Rough idle and stalling is usually from forgetting to reconnect the MAF after a filter change or a very dirty throttle body. The disconnected MAF usually causes several codes that will light the CEL.