I've started hearing a griding noise (like metal parts rattling around in a coffee can) when i accelerate from a stop, and when the tranny shifts (at around 30 mph). the car has 108k miles on it. it is starting to kick a little bit when shifting down from overdrive at around 30 mph too. is this a tranny problem or something totally different? i havent changed the fluid in a while..bad i know. should i take it to to a tranny shop and have them diagnose it or just flush the tranny and refill? thanks in advance.