Not sure if these are related, but I got a new battery and now the Blazer will idle low when I am parking it (will range anywhere from normal 600 to about 200 rpm).

It sat in the parking lot with a completely dead battery for about a week and when I started it the check engine codes had been cleared (EVAP stuff that Michigan doesn't care about). Those returned after a short drive, but the idle thing is still happening. Could the computer of lost a setting or something when the old battery died?