Hey guys, 2003 es300 and I unhooked the battery cables to clean them and when I hooked them back
up the car starts fine but will not idle. Tried driving it for awhile to see if it would "relearn" but I'm having no luck.
HELP!

 

First thing I would check is that there are several small vacuum lines right around the battery. Make sure you didn't disconnect or damage one of them, or loosen a connector to the intake system. Those hoses get very brittle with age (heat) and may need to be replaced.