It's not pretty, but a little oxidation is to be expected, right?
Inside, things take a turn for the worse:
I'm not too alarmed yet, I've read approximately ELEVEN BILLION PAGES of E30 related stuff and know that a bit of oily crud in the intake tract is nothing to get excited about. And after the air filter and plugs I'm getting desensitized to dark wonders of this engine bay. If I want to fix the idle I should be looking for vacuum leaks, which is easy because they're everywhere!
Why spend all that money on a silicone air intake boot when you can just cover your cracked-to-shit rubber boot in silicone? You'll also want to note the electrical tape on the broken ICV-air boot connection, and the discerning eye will also see the pressed-in throttle housing fittings, which are no longer pressed in so much as being trapped in a thick layer of baked on greasy crud. All the other hoses were dry rotted into oblivion as well, some taped up some not.
The throttle housing didn't fail to fail to disappoint:
An even less flattering angle:
I didn't notice until much later when I was reassembling, but the throttle linkage was nicely bent. Next pic makes a good visual representation of my sanity at this point: superficially intact, but cracked to the point of being completely nonfunctional.
And way down there at the bottom of the throttle housing was this poor guy. You can't really see it here but it was completely full of oil. I took it apart, cleaned it, and drilled a tiny drain hole in the bottom of the casing.
The O2 sensor had more problems than just being unplugged:
I gave it a good soaking in Sea Foam:
After the crud was loosened up a bit I cleaned it up as much as I could, plugged it back in, and no more O2 sensor code! Of course the CEL didn't go out, either.