When was the transmission last serviced? The 4T65E really do not like dirty or burnt fluid.
Have a scan tool that can read the transmission controller? If so or you can get one take a look at the line pressures and the shift adapt numbers. If they are maxed out it is likely that the pressure solenoid is sticking.
What I would probably do is to drop the pan, replace the filter and clean any crud up, then refill with new fluid. Remove the battery cables and hold the two cables together for about thirty seconds. That will erase any learned transmission adaptive settings. Then start it up and go for a normal drive for twenty to thirty minutes.
See if it improves. If not you may want a transmission shop to run a pressure test and see what they say.
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Wednesday, October 11th, 2017 AT 10:42 PM