The torque converter must have some wear and tear on it. How many miles are on the trans?
The 100hp tune in most cases is not going to throw the trans in limp mode unless the trans has either high miles or hard miles on it. I would recommend running tune 4 most of the time, or locking the truck out of O/D in the race tune.
As for the trans relearning I would give it 100-200 miles of mixed driving to completely learn the new tunes. It may hold the bigger tune a little better after that but if its limpimg it easily I wouldnt expect and miracles
Id be more than happy to turn the race tune down for you and email you that update if you would like. -Bob