Depending on the year, it's a very definite possibility that it's just a normal cam thing. I have a '97 GTS and by the way it idles you'd swear I was running an aftermarket cam. I had the car in for a flywheel install yesterday and made a point to ask the Viper Tech (a very good one) if everything was as it should be. He said "yes, definitely", and that based on all the cars he's driven there seems to be a noticeable difference between some of the production years.