Has anyone else experienced any power loss on their car? My car has 30K miles and they are mostly highway. I have completed the update over the winter regarding the vehicle feeling "limp" during cold weathers, and now I feel like its coming back. Recently went in for service and the SA stated that there is a bulltin on this issue and it states that its due to carbon build up and requires a carbon clean out about $150. Is this necessary for a 30K miles vehicle? Is it apart of the service?