it could be many things... from spark plugs, fuel filter, air filter, PCV valve... this last one is the most common cause for low idling... there is a screw on your throttle body... rotate it counterclockwise and it will allow more air in your engine... if this doesnt solve the problem.. try changing the stuff I told you...^^ anyways on your DX the IACV valve is light green and is located on the throttle body... it has 2 hoses attached to it...