2004 4l80e hot trans on hills

There is a difference between the old style "flush" and the new fluid replacement. The reverse flush is what put junk where it shouldn't be. Fluid replacement just pushes new fluid thru the same paths that your trans does all the time. Replace or really flush the cooler, it is a major cause of failures. I notice the OP hasn't responded to the secondary check of temps question unless I missed it.