Do you mean a single click, and then the revs rise? It may just be the Air Con compressor activating, this would put extra load on the engine and cause the increased idle revs. Try turning the Air Con off, and see if it still happens.

I believe early Sedicis' developed a rattle from the vent ducting tube behind the dash, inserting a piece of foam between it and where it's touching apparently solves the probtem.

Don't know about your other post RE:door noise, but if no one here can help, you could try the fiatforum, although I don't think there're very many in the Sedici section.