I have a 2004 automatic n/a V6 with about 170,000 miles. I recently changed the battery and after a day of driving without any problems it started to idle very low, around 500 rpm and would shake the whole vehicle when I would come to a stop. It doesn't happen when I first start the car, only after I start driving and come to a stop. It seems to run fine at higher speeds. Any help would be much appreciated.