Okay, it's been a while now and the "fix" I mentioned a few posts above was perhaps only a coincident. After a couple weeks the noise had gotten worse and the mechanical "bzzzz" heard on the recording in my OP has been replaced with loud rushing air (boost leak, but from where?).

So, a while ago I replaced the intake elbow gasket (not fun) but this did not fix the issue. [One of the holes in the manifold was stripped out but I was able to get it back on with a decent amount of torque. Hoping I never have to remove it again. If I do I may need to retap the hole. ]

Later, joining the party was a slow oil leak/drip on my garage floor. A visual inspection appeared to suggest the source was the EGR valve. So, today I blocked off the EGR valve in both spots using two block-off plates. Alas, this did not fix the issue, although I am glad to have that done anyway. No more soot. (Yes, a GDE tune is coming soon when funds are available in the Jeep budget).

Then I came accros this thread which seems to match my issue, although the OP does not mention a boost leak. viewtopic.php?f=5&t=76943

My plan: Next weekend I am going to pull the FCV valve. (I am pretty sure you guys got it right the first time. ) Depending on its condition I am either going to replace the gaskets and re-install it or I am going to delete it and run without one. (Thoughts?)

Couple questions:

[*] To do the FCV delete, I think I need shorter bolts. Can someone who has done this tell me the exact specs on so I can buy some in advance?
[*] Would now be a good time to replace my glow plugs? Will I need to remove the intake elbow from the manifold to do so? I am hoping not since I have that problem (stripped out threads in manifold) as mentioned above.

Thanks!

Oh, and pics of my EGR delete below just for fun. I just left the coolant lines in place.

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