IAT is Intake Air Temp and you have to use the teg one of those. I used my civic one for a while and it messed up a couple of settings... It's the white sensor on the right-most runner in the pic you posted above.

I don't know if you could use the EVAP from the civic. I don't have my EVAP plugged in and it works fine. :dunno:

I run an OBD1 ecu and I don't think it's necessary to have.