Well, got lots of lookie-loos on this thread, but no suggestions? Great. Well, at least I can leave some resolution for posterity who may be experiencing similar issues.
Days of searching here at PSO gave me nothing to go on, so I decided to hit teh googlez. That lead me to TheDieselStop.com, where I found several threads which implicated the injectors. TDS was also where I found the link to this brilliant fellow's video: http://youtube.googleapis.com/v/GHwjEfJtM_g&hl
. Fix your truck for a quarter, WITH a quarter!
Fortunately for me, I didn't have this problem (yet), but perhaps that's to come. Either way, I'll be ready!
Further googling took me to FullSizeBronco.com, where I discovered this little nugget: GB Remanufacturing - Tech Bulletin #103
, GB Tech Bulletin #103: Ford Injector Driver Module (IDM) Replacement. Following the instructions given there (downloaded as a PDF using the link at the bottom of the page), I disconnected the IDM and ohmed out the harness to check the injectors. All of them came within spec, whether at resistance or open, which cleared the injectors, UVCHs and harness of any issues (for now, of course- this is why I don't yet need to do the quarter mod, although I may do it anyway just to have it done and not worry about it).
So, that left the IDM as the most likely culprit. Luckily, I have a 'spare' from the '97 engine donor! Plugged it in and bolted it down, and she started like nothing ever happened. WOOHOO!
So, three months almost to the day, and my big ugly girl is back on the road. I hate to think that the issue with the old engine (see thread "I think she's dead, Jim..." at I think she's dead, Jim...
) was just a dying IDM and perhaps a blown oil cooler, but it's entirely possible. That would make this a VERY expensive case of mistaken identity, owing solely to my ignorance and impatience. But, as the generous old coot who donated the space in his barn for my swap is often heard to say, "All's well." Even if I spent twice the money, having my truck back is worth it.
Hope this helps someone somewhere down the line.