I recall reading you've had nothing but problems with your truck... And your not the first to report gear selection/bogging problems either on these gas trucks as your tranny is the same as the 6.4. I don't believe a tuner going to help you with the bogging issue when shifting from 1st to 2nd.
Hope you get it sorted out....
Yup, had to get it towed again last week when a rear brake seized and over heated. I talked to a tuner specialist who guarantees satisfaction. Although it won't change the gear ratios, it will change the shift points and make them occur sooner. It should get rid of the 4th gear starts but won't help with hill climbs with the tt.