The sunroofs on these cars are notoriusly fragil! On each side of the slider there is a lifting angle whice is made of potmetal and plastic and they are eager to break. Lifting angles must always be replaced in pairs because there have been so many updates. The rat tat tat you are hearing is the cable jumping teeth at the motor (not good).
As far as your idle; I would dump a bottle of Techron in the tank and see if it cleans up the idle. As Larry stated put a set of copper core plugs in it also.
Good luck Mike