Have a mechanic check the operation of your EGR (Exhaust Gas Recirculation) Valve. When the car is in park and at idle the valve should be closed. When the car is being driven the valve opens and recirculates your exhaust gasses. Hense the name... This can effect idle and stalling issues. There might be some carbon build in there.
There is something else you can check. Very simple. Take a look at your throttle body. After time carbon builds up on and around the throttle plate.
Just use a clean shop rag and some carb cleaner to clean it out. *tip* place a rag underneath the throttle body to soak up the carb cleaner.
I hope this will help you out.