2000 Rough idle and tapping sound

I have a 2000 gallant es 4 cylinder. It idles rough and makes a tapping sound. It has always done this since I first purchased the car. Is this normal? What can I do to fix this? The car runs fine and the tapping sound goes away when the idle reaches 2. I have had no real problems with this car besides the timming belt that blew at 106k miles. I did get a new head and timing belt put in by the dealer. If anyone has not checked their timing belt, within the last 50 k miles, I suggest you do so. The job would have ran me around $450-$500, but since the belt broke and the valuves bent it ran me $2.300. I was just wondering if there is a way to get rid of that annoying tapping sound?
any help is appreciated.

Thanks
George