This got me thinking about the way that area of the book was structured, and I realized that what felt wrong yesterday was the order of events; the piece I was working on didn't feel like it flowed from the events right before it. So I rethought that portion of the story and moved the scenes around, getting them into a lineup that feels better to me. Now, at this moment, it all seems workable.
If it is workable, I'll have well over a hundred pages of the book done once I get this next part smoothed into cohesive scenes. Will have to wait and see, though.
I also had the thought that I should remember to tentatively plan to alternate exciting stuff with slower info-heavy chapters. I don't think this is possible all the way through, but if I keep it in mind as the goal, it should help keep me on track.