What causes a 700R4 to stack-shift (short-shift through gears and lug)?

Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.

• TCI says not to tune shift timing with the TV cable: governor weights and springs control shift timing, with lighter springs raising the WOT shift rpm and stronger springs lowering it. (LS1Tech)
• Per TCI, very-light-throttle shifts should fall around 15-18, 25-30 and 40-50 mph; tire size and axle ratio change the speed reached at a given rpm. (LS1Tech)
• Per TCI, moderate-acceleration shifts should be about 1-2: 15-20 mph, 2-3: 25-30 mph and 3-4: 40-45 mph; a too-loose cable causes soft, stacked shifts and the instructions say to stop driving and readjust immediately. (Corvetteforum)

Confirm against the instructions for your exact parts before wiring. More: Transmission control in our tuning guide.