[gumby79]

Install an EGT (ehxsost gas temperature) gage with a "fast response "prob . Then apply target Egt technique similar todriving with a Vacuum gage except yout target is the lowest temperature to maintain speed instead of the highest Vacuum . For my 1st gen cummins its about 500°f on flats 600 Med grade 700f heavy and 800 for major aka 7%and up ,all at 65-60mph (my trans will not hold OD above 800° below 60mph).
Some times on a grade as the rpm drop the EGT will rise 50-100°f with no change in throttle. in theas situations back off the throttle and maintain your EGT set point . I recommend the "fast response " because with my truck the needle moves at the same speed and ratio as my foot.
Just reducing the pressure but not the position will sometimes result in a 25-50°drop and will cause acceleration. Dont understand the physics behind it ,but it works.
I think the region should show up on the EGT gageas well .