This particular engine responds to an overly-lean LSN setting in a way I'm not accustomed to; rather than idling high, it stalls after a few seconds of idling. I ran into that multiple times while initially tuning the engine, which led me to err on the side of a slightly rich LSN setting. I dialed-in the HSN setting weeks ago, but I've had to fiddle with the LSN and idle-gap settings almost every run in an attempt to find the best balance between air and fuel when idling. It's just a very finicky carburetor compared to what I'm used to. But today the engine ran well; it seems to be happier with a slightly leaner LSN, a newer glowplug of the same medium heat range I was using before, and the warmer weather we had today. It chitters a little bit while coasting, though, which tells me the LSN setting is a little leaner than ideal when the engine is hot from a full-speed run -- but I suppose that's better than having the engine stall when accelerating after idling for a minute. Multivariate problems are always a pain to troubleshoot.