T-com locks up the converter when it wants to

[1st and goal]

I'm running a 4L60E with a T-com and a Vigilante multi disc torque converter in my 94 Z/28.

I took my Z for a few tuning trips down the local racetrack and I had the WOT TCC lock-up box unchecked and the min. MPH for TCC lockup was at 55 mph but at about 90-95 mph (not really sure of the mph as I wasn't watching the speedo) but I felt the t/c lockup (and could see the rpm drop about 600 rpm in my fast data log).

I then unhooked the TCC 4L60E wire connector and went for another rip down the track and the Vig didn't lock up so it's not the converter.

The T/C does lockup at 55 like it should under gradual acceleration.

I checked the global setup parameters and I'm exceeding the min. TPS for WOT %.

What do I have to do to the T-com to not make it lockup when the box is unchecked? (other than unhook the wire)

I have yet to try and see if it locks up when the box is checked at the appropriate mph as I only had a few trips at the track.

What is the minimum mph that you can make the t/c lock up at? I was looking to do some second gear pulls to do some street tuning on the fast system.

Marc