My 05 has this vibration sound in cool weather or when it rains. It only occures when i sit at a stop light/sign, or just sitting ideling in gear! And also when i run the AC.. It sounds like im parked next to a bus or a semi. But when the weather is warm the car is very quiet. I bought it used in 06 and had the problem since. I have had it in the shop time after time and they can't find the cause. They even replaced the engine mounts with no luck.. It now seem's to be getting a bit louder over the yrs! I luv my truck but this is getting old... Anyone out there have this problem?