The EGR has been plugged since about day two of my ownership. I'll unplug the AC clutch thing - AC doesn't currently work anyway. I'll also disable my fuel heaters to eliminate them as culprits.

As far as the lift pump goes, it has been off the car for some time. I recently reinstalled it and have kept in place the electric pump that I used with WVO - so I actually have an electric pump feeding the lift pump. Just to be sure, we're talking about the thing on the side of the IP that has the manual purge pump on it, right?

The only idle adjustment I know of is on the "engine" side of the IP, held in place by a lock nut. Loosen the lock nut, and turn the screw clockwise for faster idle, counter clockwise for slower. This is what I've been doing, anyway.

Today, it would always crank back up after cutting out. In the recent past, it didn't do so until the next day or much later in the day (I usually have to wait overnight 'cause I gotta sleep sometime in order to deal with my high school students with some amount of decorum the next day ...).

FYI - This issue didn't happen suddenly. For a long while (perhaps 3-4 months), it would stumble at an idle, particularly if my fuel blend was thinner than usual (a higher percentage of diesel). I blamed it on clogged filters, air in the lines, etc., and didn't think too much more about it. It eventually got worse, then one day after a secondary filter change (filling with Sea Foam, as was my custom) it didn't start back up.

Great improvements have been made recently. Perhaps another diesel purge or some other cleaner will continue to improve the situation.

Keep up the suggestions, and I'll keep working on it until she's reliably back on the road. Thank you so much for your help!

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)