2004 Malibu Classic 2.2L Rough Idle

[sixseas]

Hi I have a 2004 Malibu Classic well maintained 2.2 L engine 20k miles. When the engine is warm in drive at idle, the engine shudders vibrates the dash and steering wheel. It idles smooth when cold. In drive it settles to a base idle about 575-600 RPM. When I raise the RPM with the peddle just a bit maybe 50 RPM it idles perfect. Otherwise the engine runs perfect, air cleaner and plugs are like new. Is there any way to adjust the idle up or identify what sensor controls the idle?

[sixseas]

I took the idle air control valve off the throttle body and cleaned it. It appeared the valve was stuck and carboned up gently pulled it to full length of the spring. Then cleaned the head and spring area as well as the socket with alcohol. I ran it around 100 miles today the car idled smooth hot or cold with the air on or off. It also looks like its getting noticeably better gas mileage. Seemed to simple a fix but she is running and idling perfect all day today. Prior to cleaning the valve it always shuttled when warm, in drive at idle actually so bad the dash and wheel shook. So think I got it.

[Tech II]

Cleaning the throttle plate and bore go together will cleaning the IAC pintle and passageway....