if this is the 243k miles trans you mention in another thread,
Its about the 4L60e tranny in my 2000 5.3L yukon (243,432 miles on it and just went for the first time
The trans is done, finished, kaput. 243k miles is 2.5 times the average useful life of the 4L60e trans.
Pull it out and have it rebuilt properly. There is no magic elexcer that will fix it. there is no magic adjustment