The Intake Air Temperature sensor (IAT) is a vital part of doing a proper speed density conversion. The IAT should be placed in the intake pipe far enough from the throttle plate to be BEFORE the IACV hose connection.
Wiring of the IAT sensor is very straightforward when connected to the ECU EGR temperature sensor input.
The polarity of the wires does not matter.
One wire of the IAT goes to the EGR temperature sensor input signal. The other wire goes to either pin 21 or 29, which are both sensor grounds.
If your ECU does not have an EGR temperature sensor input, you will need to connect the IAT to one of the NEMU ADC inputs using an external resistor as shown below.