Hi Aaron,
If the ecu is controlling the Throttle plate position, there is a difference between the "off" position and the 'zero' position.
My '07 Avalanche is fly by wire, it caught me off guard until I realized that the fully closed position is way different than the "off" position.
This allows it to adjust at startup without hitting an 'end stop'.
You need to check the idle position with the OBDII scanner to get the correct position for the groove. Once you have that you can pull the TB off, leave it plugged in, turn the ignition key to the 'on' position so the ECU and scanner will talk and you can move the throttle plate to the idle position by watching your OBD scanner. If this TB is like mine there is not enough room for a credit card or anything else so you will want to take your bit and scribe a line in the TB wall as a guide for the groove.
You'll find it necessary to hold the plate in place while you apply the groove.
This is the "off" position
This is the "idle" position
Ain't this fun
Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma