I installed my heat shield (Randall, thanks for the pic), but it was in contact with my linkage in three spots, so I took it back off. I then cleaned and adjusted everything again, including centering of the jets. The pistons drop down nicely with a metallic click.
So, after three assemblies and re-assemblies (I tried the heat shield twice), I went for a drive.
Here's what happened. The idle raced, and even seemed to accelerate between shifts. At one stop light I was idling at 2000 before kicking the throttle. Each time I kick the throttle, the idle comes back down. Over twenty hours of messing around has got me nowhere. I'm back where I started.
I've looked again at the linkage. It does appear I'm binding after all. Pushing with a long screw driver, on the same lever where the little throttle springs go, does seem to knock the speed back down. And it's both sides. Here's a picture of the lever I seem to be able to move--stock pic, not mine.
What's the deal? Why all of a sudden and all this hassle? Also, is WD40 not good enough to loosen the bind here? Some magic grease needed? I'm inclined to suspect it's more than a grease issue.