REF I have the same setup as you, minus the fresh tranny.
I'm interested in your new tuners performance. My DP tuner is my first tuner experience so I have no reference as to how it should perform. I have 20,40, 60, 80 & 100 hp tunes. The power increase in the 20hp is pretty amazing. All the other tunes dump so much "rolling coal" I rarely use them. But even in the mild 20hp tune I have to drive with the EGT gauge rather then the throttle when climbing a Colorado mtn grade.
It seems that a 4 speed auto on a +8,000# van is subject to critical shift points and gearing to keep from "rolling coal" all too often.
Looking for your feedback on the new tranny & tuner combo.