i bought my xb about 3 months ago and have noticed that my dash is starting to rattle,somtimes so loud it over powers my radio,it drives me nutz,i put after market speakers and a amp in my car about a month ago, and the sound disapeared, but now it has a come back and seems to be coming from the ac vent on the drivers side,by the radio, has anyone had this problem?

http://fourthgenhatch.com/scion/tsb/04xbrattles.pdf