I have a 1994 Taurus GL Vulcan and I think I have a transmission problem and was wondering if someone could help me. Whenever I am at a constant speed for a while and left off the gas, it sounds like my trasmission makes a thud sound like the gears are catching or something. It can be felt and heard. It's not really loud, but you can hear it. Can someone help me understand why it does that and what I can do to stop it. Thank you.