Speeeeeeaking of eejits, I drove it the other day. Somewhat cooler weather, and it was acting all glub glub rich, too much fuel! So of course I set about driving it around some, doing a bit of autotune, doing a bit of smoothing, got it all running nice and clean again. Then... I happened to notice I'd left the IAT sensor unplugged after removing the cold side piping to refit that BOV. So basically it thought it was -100 bazillion degrees air temp.
That did remind me though, the IAT has always unwaveringly said '70 degrees' - and I'm pretty sure it's not a wiring issue - because if I unplug the sensor it goes full cold, and if I touch the wires together (briefly, hopefully that's not bad, ahem) it goes waaaay hot. So it seems like the fixed resistance is coming from the sensor itself. I bought another one, we'll see if that works.
What are the odds it needs a pull-up resistor? Is the sensor meant for 5v or 12v? What does MS want to see.
Dumb questions and I'm sure you've already considered that, but worth asking.