Hello let me start off by saying I have been a LONG time lurker. There is a wealth of knowledge on here. I am rebuilding a "towing" 4l60e for a family member exactly like how I built mine. My transmission however has a slightly weird 2-3 shift only on moderate-heavy throttle. I'm basically want to build theirs exactly like mine minus the weird 2-3 shift (hopefully).
So the shift feels like it slightly lunges forward then slows down slightly then resumes as normal. The shift is quick just feels odd. Feels like two different steps. All other shifts are great.
This is in a truck behind LM7. I have .032-.035 dry clearance 3-4 clutches, .085 clearance servo pin. Pinless accumulators, Transgo shift kit, Sonnax 2-3 HD shift valve, corvette servo, super hold 4th servo, wide band, Sonnax Line pressure booster kit, 1-2 hole:5/64, 2-3 hole: 7/64, 3-4 hole:7/64, band release: 3/32" and a "high" stall 1800-2100 RPM converter.

 

You should next take Line-pressure readings for all the Gear Ranges at idle and at 1,200 - 1,500 RPM.
Also while driving when the 2-3 Shift occurs.