My 89 coupe (original trans) is pitching forward and back when I'm coasting to a stop in gear (not downshifting). it seems to be the worst in 3rd, downshifting helps, coasting in neutral is no prob, no noises coming from trans other than normal gear whine. My guess is this is normal wear for a trans of this age...it has been fine (smooth) up until just these last few months. The clutch was replaced about two years ago.
thx for comments, Mike