Howdy folks. I've been chasing down and dealing with complaints with excessive rpm flare between gear shifts 3-4, 4-5, 5-6 on the 2016-2017 68rfe models especially. The older models do it some, but the 16-17 models do it terribly. Bottom line tuning can't fix it.
What is going on is the Torque Converter Clutch (TCC) unlocks between shifts during normal operation. Well the 16-17 models have a "looser" converter or one that has a higher stall speed than the older trucks. When you combine a looser converter with the normal TCC unlocking between gear shifts, well you get a rpm flare that we cannot fix with tuning.
If you want this gone, you have to change the converter unfortunately.
Double R Diesel, LLC