control valve

Yes you can, but often with out much success, but it is worth a try, use a good quality throttle body cleaner and see how it works.

Mark (mhpautos)

Or can it be something else, my car idles rough at a red light and stalls when I put it in park.

This is probably a faulty IAC valve, try a clean first and run a scan for any unresolved fault codes.

Mark (mhpautos)

that sounds expensive is there an alternative?

No, do not bother with used units if faulty, i do believe that larger parts stores there may do free scans, try pep boys.

mark (mhpautos)