miker_types

hey guys, before you jump on me for not running a search, i did, and it was all tranny related, well im at 144,000 miles right now, and i just got a pioneer navi installed, well i was driving home from work and when i get to a red light, my car kinda trembles when im at a complete stop as if its gonna shut off on me, but when i lower the radio, at a low volume, it doesent do it anymore, just had a semi long trip last nite, and everything seems to be driving fine, shifting perfectly, could it be the battery( 4 months old)?, tranny?, navi sucking up power?, i really dont know and im really worried , well any help/advice would be greatly appreciated,
thanks in advance