My XFire has 6400 miles on it now and it purrs like a kitten. I have to look at the tach to make sure it's running.

Maybe you idle is set a little low as suggested above. You could try a tank of UIltra 93 at Sunoco if your present filling station isn't up to snuff on their octane ratings. Whatever it is shouldn't be describe as "normal". If that is normal, then mine perfect idle would have to be "abnormal".

Bob M.