I had this EXACT same problem on my '04 with about 204K mi. My mechanic put in a tans fluid additive (unfortunately I don't know what) and it solved the issue completely. When I was talking about it with him he said his go-to transmission guy said it was known issue and suggested the additive...
@LX470MK Do the steering wheel controls still work? What does the voice command button translate to in this system? Thank you for the write up! Please let us know how things go as you use it more!