My 2007 cobalt SS/SC has lately been making a whistling or wining sound when my car is idling. The sound seams to be coming from underneath my car. I can only hear it well in idle but it does it all the time, the engine noise just blocks it out. the sound does not speed up ever but it sometimes just goes away breifly. has anyone had any issues with this?? also transmission had been getting louder lately.. could the whistle be a spun bearing in the tranny? Thanks.