Hey everyone -

So I've been chasing down this problem for about a year to no avail and I'm getting really close to selling the truck (which I don't want to do because I love it) unless I can figure this out soon.

1991 22RE Base Model (No P/S, no AC)
201k miles
5 speed manual

When the truck warms up a bit, I get a pretty frequent but intermittent bog / stutter / misfire when I accelerate. I don't have a tach, but it seems to happen between 2k and 3k rpm, and then once I get past the sort of low-end, it perks up again and feels fine. Sometimes from a stop it'll bog down and barely lurch forward for a few seconds before "catching" and driving ok. And, most frustratingly, sometimes the car will just immediately die when I start it, but only on hot starts (and, weirdly, more frequently when I park uphill like on a driveway). Sometimes it starts but keeps dropping idle, so I have to press the accelerator just to keep it from dying. I brought it to two different mechanics and they basically charged me $180 each to tell me they didn't know what it was.

I've so far done / replaced the following items to try and solve it, but it seems to only be getting worse:

Fuel Filter Replaced
Spark plug wires replaced (NGK)
Distributor cap replaced (OEM)
Distributor rotor replaced (OEM)
Air filter replaced
Spark plugs replaced (NGK)
Timing chain + tensioner (OSK)
Idle Air Control Valve Replaced
Alternator
Battery
Dipstick
TPS adjusted
Valves adjust to .008 and .012
Throttle body cleaned / gasket replaced
Intake manifold gasket replaced
Fuel injectors rebuilt
PCV valve replaced
Thermostat replaced (OEM)
Muffle replaced (Walker)
Downstream O2 sensor replaced (Denso)
Ignition timing set

A few things I've noticed:
I can't set my idle at 750/800 without it chugging, so it is set higher
The temperature reaches about 12 o'clock on the gauge before dropping to like 10 o'clock.
The problem is worse when the car is hot. Cold, it drives great and starts right up
I get a bunch of black smoke and a terrible smell when it does the bogging either at start up and while driving
I found a disconnected ground between the alternator and block - I reconnected this and my idle got smoother but the bogging is still there.

Any ideas? Really at my wits end here and I don't know who else I can take the truck to without them charging me more money to do nothing.

Here are some videos trying to show what I am talking about. The first one shows a warm start after driving uphill on my driveway. It had died right away like 5 times before the one I filmed - of course it would start when I film it, but you can still see that it has a hard time starting and idling. The other 2 videos attempt to show the bogging, but it is kind of hard to see / hear.