4l60 E 2-3 Shift Flare And No Line Pressure Increase

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On a 2000 K1500 5.3 with a 4L60E Trans I cannot resolve an issue with poor 2-3 and 3-4 shift and 0 increase in line pressure (static @ 60psi) however I do get increase in Reverse as expected. After overhauling 3 times to verify good mechanical function and replacing every electrical transmissioin component and then also overhauling a core (in case of case problems) I still cannot resolve the problem. There are 0 DTC. If I attach a Snap On scanner I can get the trans to work properly through manually lowering Pressure Solenoid amperage to get a line pressure increase. I have checked all ground connections and Pressure Solenoid wires from ECM to Trans. I've replace TPS, CNK Sensor, CAM Sensor, PRNDL Switch without success. Any ideas?