Originally Posted by SlickGT1

Search my threads. You don't need to rebuild. You most likely need new solenoids for the valve body. About $600 and a whole bunch of hours. The rough 1-2 shift when cold is about normal for these cars. Almost every v8 x5 I have driven has done this when cold. If your reverse is slow to engage when hot, could be solenoids are gunned up. I may have caused this on my car when I did my trans filter service. When I got the solenoids out, they had rubber filter type of material in the screens. You never know what someone did before you, and your solenoids may be in the same boat.