Have a 2022 f350 dually, need help diagnosing the trans any advice will help thank you

So I’ve had my truck for about 2 years now and the transmission is acting funny, I do have my truck deleted and it is the original transmission but this is the first time I’m having an issue with this!

The truck can’t go faster then 70mph and my gears on my 10 speed specifically 7-10 are acting strange like it doesn’t want to slip in to the gear.

I was just gonna go with a second speed transmission and tune it to see if that solves the problem

Let me know if yall have any other solutions but I think a new trans would be good