Since my '99 was in the shop today I drove my parents' 2000 Duratec to work. Well, you know how after you shut off a car it makes kind of a ticking sound for a while as it cools. I'm not sure if it's the cats or what that make the sound but all cars do it. Well this car does it a ton, way more than my '99 Duratec or any other car we've had. Could something be wrong here?