I have had similar probs with the celica.
All you can do is crank your stero and find each rattle or vibration individually and glue it down and/or fix it so it doesn't rattle! It's a long and tedious process but I don't know that there is any other way.....ahhh the joys of subs!
(on the other hand you could just turn it UP untill you can't hear the rattles and vibrations.....works for me...hehehe)