I don't think my engine (89 22re) has the additional linkage shown in the photos. I'll double-check it tomorrow to be sure.

I'm starting to suspect the last trip to the red caused some valvetrain damage. There is what sounds like a rocker arm knock around 1500 rpm. If it was a bent valve, would the noise be consistent at all times? This noise seems to come and go. Definitely, it was there right after coming down from 6.5k. On a cold start though, no noise. I think I need to drive it some more to get a better sense of things.

Interestingly, the stuck throttle started when the weather got cold, was file all winter, and started again when the weather warmed up.