Toyota Repair: Transmission problem, service bulletins, transmission leak

Question
I have a 2005 Avalon and have the same problem that someone asked you a few months ago. When you slow down to 3-4 mph and step on the gas the RPMs go up and the car takes a few seconds before it'll move. that can be pretty dangerous whenyou are in the middle of an intersection. I had my car at the dealer today and they said it was normal. After I questioned the dealer some more I was told that there is a chip for your transmission that can be changed, but you will lose 2 to 3  miles per gallon. I then asked about ordering it and I was told they can't get it anymore.HELP!!!!! I want my old Camry back.

Answer
I have never heard of this chip they were talking about, there is no such thing available from toyota, I have checked to see if there are any service bulletins and there are none.
Is there a warning light on the dash on?
Has the deler checked for a transmission leak which may cause the fluid to be too low which will cause a shift engagement delay.