(I didn't edit your post, I just hit the wrong button.)
That's a standard GM part of the vintage, which should be available anywhere. You may need to adapt the plug.
Last time I needed to get some, I got it from Marren Fuel Injection (
www.injector.com, IIRC.) The plug on the thing is different, but it came with a pigtail adapter - I used the tail off of the old sensor for the other end, and had a short adapter plug for squat.
Save the TPS and HEGO, most of the sensors on the RENIX engine are fairly standard GM parts, which actually makes them much easier to find (because GM sensors are often used in kitbuilds and conversions.) Dealing with Marren should allow you to replace most of your sensors for a reasonable price.
Oh - and it's "IAT" for "Intake Air Temperature" sensor. Just so we're all on the same page...