TRNW-2: 4L60E 2-3 Flare Question

[Tony's Autoworks]

Hello group,

Got a 2001 Chevy Suburban with a 4L60E and it flares on the 2-3 shift.
It does not happen all the time but will with medium to heavy
throttle. I installed a unit that I had on the shelf and on my test
drive I had the 2-3 flare. I cleaned the MAF and thought it had gone
away but the unit only lasted a week and it came back with no 3rd or
4th and the transmission temp light on and the unit was overheating at
idle. Figured I had a cooler blockage and replaced the radiator and
rebuilt the original unit that came out of the vehicle and installed
it. Still getting a 2-3 flare. I replaced the MAF with no change.
Transmission is not overheating. The only thing that is the same
between both units is the new torque converter. Could the torque
converter cause a 2-3 flare? or do I have something else with the
vehicle causing the issue?

Tony