When does the distributor need replacement?

[Samistine]

just to show odd things happen. (random)
my 96 had an  induction air leak , the top rear huge aluminum air pipe (maf to TB) had a rear left (right facing it) mount snapped off, it as just dangling on the head mount it fits to.
this was sucking air like mad causes MAF to read wrong, causes what is called UN METERED AIR. (and power loss and surge as engine shacks and crack size varied, yah nuts.)
wild effects it caused,
so finding problems can be very hard.\

OXYGEN (B1S1) Front)
o2 (front) pulled forces righter mix, fuel. and runs better , so that big  hint says engine fueling is (was) lean.
ever run the 02 sensor in the full O2 meter mode, plotted, and drive. like below.



this happens hot idle or light flat cruising at 45mph or near.

the front 02 swings, that swing is a loop, (firmware ECU ) that adjust fuel mix 6 times a second about. the ECU hugs for perfect fuel mix this fast,  see it below.
note the center point too, not offset. it swings near 0.45vdc. center point, O2 goes off line WOT normal, so only do idle and easy steady cruise , right foot steady./


and exhaust manifold crack or gasketi bad sucking ear wrecks the front 02 horrible. or just enough,  air is 20% O2 so slams the sensor to death 20 times to much 02.
the bottom header end DONUT  ring gasket bad, or loose or clamp bad too , same thing. bad.

any good scan too can plot any sensors an for sure 02. and do and X/Y plot. live in real time (near enough)

Unfortunately the tracker computer does not seem like it wants to set codes or even put things in pending. I can unplug a spark plug briefly and no pending codes get set unless I leave it disconnected for a few seconds like >5. Unplugging the OBD sensor took several minutes to set a code and turn on the check engine light. I use a portable engine monitor and a wifi obd adapter to phone and neither sees any pending codes.
Misfire/or whatever it is maybe every 2-3 seconds. I can hear it and feel it by putting my hand on the engine during fast idle. Engine stays still visually. I will try doing some type of logging using the OBD phone app.
I have an entire tracker for spare parts at the moment so I could try swapping things and seeing what it is.
i did. check fuel pressure last year and it passed the tests you put on your website.