You should really ask this kind of question on the nistune forum.
As for what you are seeing, a lot of things can drive that.
1: at the point you are describing, has it enough load to drive it out of close loop zone on the fuel map? if not, sounds like you will have to scale your TP to move it away from the close loop zone or just edit the map to do away close loop in that load area.
2: TP min and TP max like you described.
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