Upon arriving at home, I let the car idle and looked under to see if I could pinpoint the problem. It is actually some knocking down low. I have seen some post about exhaust leaks sounding like a knock. The car accelerates fine and drives with no vibrations at all. I can really hear this knocking when I let off the throttle and cruise to a stop. I will get it checked out at a reputable shop because I am clueless.