Disconnecting the battery would result in the engine computer losing its memory and needs some time to relearn. This could result in engine idling excessively low as seems to be your case. Some running around should solve the problem and if you wish to expedite the process, have the throttle body and IAC cleaned.
Check the thermostat, it could be stuck open or someone had removed it previously.
Sunday, November 10th, 2013 AT 12:46 PM