Sorry, looks like GAP doesn't have the TB relearn function, its on my Autel. You can go into GAP and clear the ECM adaptations which will essentially do the same thing, except it clears all adaptations not just the TB. You'll have to drive it for awhile to get the ECM to relearn all the sensors.
Before you do that, look at live data for the below (as a graph) with ign on, engine off, as you slowly depress the pedal:
-Absolute Throttle Position A
-Absolute Throttle Position B
-Accelerator pedal position sensor Circuit D
-Accelerator pedal position sensor Circuit E
-Commanded throttle actuator control
-TPS Voltage Sensor 1 (optional)
-TPS Voltage Sensor 2 (optional)
They should all smoothly increase on the graph as you press the pedal (except the sensor voltages-They are inverse of each other, one will go up, one will go down)
At full throttle, commanded throttle should be at or very near 100%. Abs Throttle position doesn't get to 100%, that's Ok.
The two Abs Throttle should be close, and smoothly increase with no spikes or dropouts, same for the two Accelerator position readings
TPS voltage with foot off the accelerator should be ~0.5-0.6v (sensor 1) and ~4.2-4.6v (sensor 2). I don't remember what they are at WOT, sorry. If I get a chance, I'll snap a screenshot at idle & WOT of my LR.