Shifting issues

[jacob keese]

I have 116,000 miles on my 2018 Chevy Silverado 3500 Dually with the Allison 1000. I am having issues with my 3rd or 4 gear is what is feels like. When I am driving in drive mode about 3rd or 4th gear my truck will have a delayed shift that takes longer than usual but what I am finding strange is that when I am in manual mode it will shift normally. The other issue it’s having is that when I accelerate at at a fast rate the truck will delay the shift and I will get a vibration coming from the truck. When I bought the truck with 86k I told the dealer ship to preform the 100k service for the transmission and that included the internal and external filters along with new fluid. With that being said I have checked the fluid and I do not have any burnt smell and discoloration in the fluid. Has anyone else had a similar issue and what was the solution.