I have a 2019 f150 3.5 eco boost. Recently the transmision has started slipping in the upper gears and a big clunk in the lower gears. After the transmision warms up it drives good and smooth, but is scary for the first 6 miles. Dealer reprogrammed TEM but it still doing the same thing. The dealer say rhe transmision has to learn my driving style. I don't think it should slip or violently shift. Has anybody had this issue and had it fixed or do I just have to live with it. Truck has 66000 miles

 

with that many miles you should do new fluid and filter and see if that helps, that would be the first thing I do to see if it improves things.

 

CDF Clutch Drum. There's plenty of threads about it and a TSB about it.