I'm looking for guidance on my 4.0 OHV Ranger EGR codes (327 EGR feedback signal is/was lost, 558 EGR vacuum regulator solenoid/ circuit failure).

Considering the 1993 Ranger doesn't have an EGR, Ford didn't start to put them in until '94, I'm a little lost on where I should start with diagnosing the issue and I'm looking for guidance on it. I have other codes as well one of which I've partially given up on, at least for the moment.
I am experience a 121 code, TPS is out of range, more specifically the voltage is too high. I made attempts to lower the voltage with the idle control screw and couldn't bring the voltage down without the car stalling out so I ended up replacing the IAC valve and attempting an idle reset procedure. From what I can tell so far, the engine is running much smoother at parked idle and is around 700 RPM. The only issue now is that the TPS voltage is even higher than it was before, now at around 1.39 V but I'm going to leave it for the time being because the engine seems to have responded well to it. Attempts to lower the voltage via the idle screw were unsuccessful because the idle would go from around 700 to 500 and back up continuously.
The previous owner must've messed with a lot of stuff and created further issues down the line. It doesn't help that there is a hole in the throttle plate with a screw in it. I imagine it was drilled out in an attempt to increase air flow and smooth idle originally. I've also replaced quite a few vacuum lines and so far I can't find any other leaks but I'm not 100% on that.

Regarding the rest of the issues, the engine is definitely not running at peak efficiency and is likely running quite rich. I'm assuming the EGR codes have a role in this. Not sure what I should be looking for, testing, or replacing. My only guess at the moment would be the O2 sensors because as far as I'm aware they do eventually get old enough and go bad. I haven't checked them yet so I'm not sure if they've been replaced at all in the past 30 years but based off the handy work of the previous owner, I highly doubt it.

Also on a side note I am getting an Engine On Code 223. Any help with that as well would be greatly appreciated as well.

 

Is this a "new" vehicle to you, of have you had it a few years and these issues just came up?

Original TPS had slotted holes so the sensor itself could be adjusted once anti-diesel screw was set(600rpms) on a warmed up engine, most now don't have that
Have a look at your current TPS and see if there is enough material around the screw holes to elongate each one so you can adjust it enough to get 0.99v, also confirm 4.5v at wide open

1993 4.0l computer can have EGR software, require in Calif sold vehicles in 1993
So its possible either vehicle was from Calif(and EGR was removed) or Calif computer was swapped in by mistake, but these EGR code should have been there since you owned the Ranger

Yes, O2 sensors last 12 years or 100k miles, they are THE ONLY sensors that wear out, my 1994 4.0l with 400+k has all it's original sensors except O2s
And yes, when they are at end-of-life they make computer run engine richer and won't set a code until you could have bought 10 of them with the money you wasted on fuel up to that point
So change the O2s when its time, and keep more money in your pocket
This is for ANY YEAR or any brand of vehicle, not Ranger or Ford specific

I had to change the 3 capacitors in my 1994 4.0l computer a few years back, 2 were bad, caused odd issues and codes, easy fix, under $5
I would pull out your computer and open it up to have a look
You can also get the number off the computer to see if it matches the white label number in the engine bay
This should be the first thing to do after the O2s because if the codes are bogus you would just be chasing your tail trying to diagnose them

 

The vehicle is new to me. Bought it out of state less than a month ago in Indiana and the title is from Tennessee. Underside definitely looks like a Tennessee truck, no rust damage.

Unfortunately I didn't have time to work on the truck today but I will look into boring the holes out on the TPS. Should I set the RPMs to 600 with or without the IAC plugged in?

I actually checked out the computer a few days ago and it looked great. No burnt out capacitors or anything out of place but I had a suspicion that the computer had been replaced based on how clean it was and the fact that there was writing on the outside. Luckily I took a picture of the sticker on it because it was a pain to get out in the first place. Maybe I'm blind but I'm not finding anything on the engine bay stickers to compare off of. Not sure if you'd be able to determine based off the picture but I figure I'll attach it anyway.

 

Warmed up engine
Unplug IAC Valve
Set anti-diesel screw so engine is at 600rpms, barely running is fine, as long as its below Computer's "target idle"
Plug IAC back in and idle should go up to "target idle"