"Stall Speeds" is a popular # and a myth. Used by aftermarket to sell TC to the pubic. GM may publish a "stall speed" because public wants this but isn't really used by GM and most others.
Your problem may not be the TC at all or maybe only partly and have wrong gearing or setup for the "dumb" 4T60 for the engine and car.
4T60 needs correct settings for TV cable, Vac Mod, and the Governor that drives VSS to even hope the trans shift right and doesn't cause big problems.
You need tools and pressure gauge(s) to setup TV cables w/ most engine swaps or will cause low/high pressure in the trans. Same for many Vac Mod.
Your best bet is go to the Trans rebuilder or another trans shop and make sure you install and setup those two parts and minimum. Trans shop can respring etc the governor if needed at same time.
4Txx often come out of heavier vehicle and need changes to the governor. Most Rebuilder won't changes this w/o more data, even then may need to change after install.
Vac Mod Need Full Manifold Vacuum. Not Ported Vacuum many ports on TB/TBI are.
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
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