Check for any broken/cracked hoses connected to the intake manifold. Your looking for any vacuum leaks that will disrupt the idle quality.
Your Idle air control valve could be stuck open or your mass air flow sensor. Some models you can disconnect the mass air flow sensor and the engine will run better (doing this will also cause the check engine light to come on) if it is the mass air flow sensor.
Check the throttle body for coking, if there is any build up on or around the throttle plate/ throttle body this will also cause the engine not to run very well at idle.
Let me know what you find or if you have any more questions.
Wednesday, January 15th, 2014 AT 7:28 PM