Noises During Shifting problems of the 2004 Lexus RX

I leased a 2004 Rx330 in January, 04. Immediately I began having difficulty predicting what the transmission was going to do next. Shift points all over the place. The "upgrade" was performed, provided temporary adjustment. Merging is deadly. I thought perhaps I was slipping off the pedal, but now know it wasn't responding. The driveline has always had a "clunk" or "thump" that occurs when lifting from the throttle. We have reported this to our local dealership (tom wood Lexus, indianapolis) on numerous occasions. The first diagnosis was "rocks under the seat!!!!" each time, another service writer would experience the thump/clunk, agree that that was not supposed to be there, and claim "I'll get to the bottom of it. " in every instance we received the standard response, "it's a normal noise. They all do it. " in mid September, the vehicle was in service for another issue, and a new, eager service writer drove the vehicle for several minutes, absolutely agreed that the noise was causing wear on something and that he wouldn't want to buy this vehicle when it comes off lease, if it does that!" after having the vehicle for 10 days to fix the other problem, the previously eager service writer told us he had driven other Rx's on their lot, and apparently the problem is a "normal" one. Obviously, we have been driving a very unsafe vehicle and Lexus/dealer don't care. Until somebody dies, potential Lexus customers beware!!.