My trans is making a hissing/sucking noise at wot.I recently changed the filter and o ring,maybe it is not sealing?it is also shifting differently,real soft and almost slipping on the 1-2,rest is firmer than usual.Anybody have any ideas before i drop the pan cause i really dont thing the o ring is the problem.Also this has been happening, there is a clunking like someone is hitting a piece of plastic at my firewall above the tranny.Or behind/under my dash/console.Has been doing this intermittently since i got the car a years ago.Does not really follow the engine/tranny rpm,doesnt sound threatning or anything but is there,anyone have any ideas,cause i am all out.Maybe distributor worn out?