2005 Buick Park Avenue

A routine maintenance battery service & testing the battery and charging system makes sense. The stalling and inconsistent idle speed could be related, or that could be another problem. What to do depends on the configuration of the idle control mechanism used on that vehicle. Checking the throttle position sensor, servicing the idle air control, and a throttle body cleaning are all something to consider. A proper diagnosis by a shop is where to start, reading out any diagnostic codes present, and a visual inspection & test drive by a trained mechanic.