What has happened, and what you are doing by touching the disconnected positive cable to ground is clearing all the adaptive memory from the controller. This will most likely not fix your idle problem because the dead battery has already done that for you.

You need to clean your throttle body. Get a new gasket, take it off and clean all the carbon build up from it. Inside the idle motor passage and from around the throttle blades. Put it back on and you should be good to go.