08 6.4 sct

[texaskingranch08]

i have an 08 6.4 4x4, 6in lift with 35s has sct livewire set to performance tune did not adjust trans settings on tuner havent had any noticable tranny problems but bought a 38ft fifth wheel camper and after pulling couple times noticed the truck bogging while pulling the trailer after about 20 or 30 min, thought it was just fuel filters so replaced but problem continues, now seems as its starting to slip while shifting noticably 3rd to 4th i believe. i found a used tranny with 9k miles how do i keep this from happening again, changing tune performance to tow every time i pull something,deep pan ? please help!!!!!!!!!!