Wow. You should get "The Car Talk Golden Globe Award" for that reply. Who' da thunk to look at throttle valve shaft seals?

To bring this hopefully valuable thread to a close, I can provide the following updates:

The injector seals are relatively new. I recently checked the throttle valve carefully before adjusting the TV Switch. I double checked it today, when I also completely removed the air screw and chased it's threads (3/8"-16) as the outside end was a bit buggered up from years of adjustment. Following your advice, I made sure the AAV (my SAAB part) wasn't passing air when the engine was hot. It wasn't.

Now, with the air screw completely seated and the AAV completely sealed, my revs are about 1000 which, with the cam I have (no idea what cam it is) that's what it needs. However, I used to be able to adjust the air screw and get the RPMs much lower, so I suspect I should start hunting for a vacuum leak.

There's a bunch of auxiliary vacuum plumbing on this thing, which has been added to make the brakes work better and boost the idle when the headlights are on, but I crafted all that myself and am pretty sure it's solid. So I'll just start going through methodically, either disconnecting and plugging, or using the old carb cleaner spray trick.

Really want to thank everyone for their insights. It's nice to have some help when trying to sort something like this out.