terminal cleaning usually include removing all detachabale objects in the room

This depends what Earth Terminal you mean

The one on the top of the battery, You may have a bad battery. Disconect it and come back in 24 hours and see if it is dead. Not dead means that there is a short in the electrical system and this terminal needs cleaning.

If the battery is dead the battery is bad, replace it.

If this is another terminal and gets hot and stays hot it means there is a large draw on the system and this terminal is dirty and requires cleaning.

The hot terminal is allways the highest resistance in the system.

Good Luck

Cleaning the battery terminals had nothing to do with the engine not idling properly. Just a coincidence.

If you do not have an actual battery terminal cleaning tool (that you can pick up at any local autmotive related store), put water and baking soda on your battery terminals and take a rough grit sandpaper and give it a light sanding or use a wire brush if you have one.

Unwanted or high resistance in a automotive circuit is usually caused by corrosion around terminal points. Start at the battery terminal connections and work your way through the circuit cleaning any terminal corrosion that you see. Take the termination apart and clean the faces that touch each other. If possible tape the joint to keep air from the connection as it is this oxidation that is the main culprit.