If the Idle re-learn procedure does not work for you, you probably may have a vaccum leak some where.
Reason why you may have a vaccum leak:
The battery is located near a lot of vaccum lines that are very very brittle. If you just bump these lines they will break, causeing some idle issues and cruise control issues and even air conditioning issues.
I suggest disconnecting the negitave side of the battery for a few minutes, and while that's disconnected tap the brake pedal a few times to release any charged voltage in the system. Then recconect the battery and perform the Idle relearn procecure.
Go here for the idle re-learn procedures:
http://www.v6z24.com/howto/idlerelearn
Good Luck,
tony