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2016 Tahoe 6L90 Transmission problem

Just rebuilt the transmission. Replaced the clutches, seals, pump, torque converter and TCM. Had the TCM programmed at GM. Ive been driving it now for almost 2 hours and it shifts great until I turn it off. When I restart the car it has a bad shift the first time it shifts 2-3 and after that its fine. When it does it I can feel it shift into 3rd and then less than a second later a harsh bump but only the first time, after that its good. Ive done a many of these 6L80/90s and have never ran into this problem before, has anyone else? VidMate Mobdro