5.3 LS fueling help

[XwalkerX]

Preface:
1972 c10 daily driver
L33 5.3 swap
4L60e
shorty headers
dry filter CAI
no cats
stock otherwise





Issue:
as of late whenever I make my weekly drive from LA to San Diego I usually get a pair of soft or confirmed codes.
doesn't only happen on long drives though. codes will pop up randomly (5 min drive around the block or 2 hour drive)

p0172 - system too rich (bank 1)
p0175 - system too rich (bank 2)


these codes started coming up about a month or two ago but I would also get the occasional MAF code so I tried to clean it (which basically is just a band aid fix IMO) but it started to stumble again
so I put a new MAF on it figuring the codes would clear up but nope.
the engine runs completely smooth since I changed the MAF though.
I can watch my live data via a wifi obd reader and I can see the pcm pull fuel then back to 0 then pull fuel then back to zero and so on and so forth. never just a steady reading.
also my though is that since I get both codes simultaneously I highly doubt its 2 leaky injectors (one on each bank)


so last night I checked the MAP sensor.
(engine off / key on) im getting a reading of 14.7 (1ATM) which is perfect.
(engine on) im getting a reading of about .2 ATM at idle and it rises as it should based on throttle input
so to me I feel like the MAP is working as it should be.


next I decided to check the fuel pressure at the rail...
so my truck has a corvette style external filter/regulator back by the tank (returnless system)
currently running a fairly new (based on the time of the swap) wix 33737

fuel pressure
(engine off/key on) 55psi
(engine on)[ open loop ] I would see 62 psi
(engine on)[ closed loop ] it started to rise to 63/64 psi and it would bounce around between those numbers pretty steadily and when you blip the throttle it goes to approx 61 psi.

from all my searching I cant find the pressure that the Wix filter is supposed to regulate to but I see that the range for the 5.3 is between 55-60 psi
so if I am getting 3-4 more psi at the rail do you think that is enough to cause the rich issue?
I ordered a new wix 33737 just in case.

lastly.
the truck has upstream o2 sensors after the shorty headers but no cats (or downstream sensors obv) both of those items are coded out on the pcm so no codes pertaining to those.
is there a possibility that the o2 sensors are failing and causing the issue based on not having cats? perhaps the lack of converters changes the heat range and thus the voltage reading and that could trigger the pcm to add or subtract fuel.
just to be clear I have not ever pulled a code (either soft or confirmed) for an o2 sensor problem.


thoughts?

EDIT: forgot to mention that the coolant temp sensor reads accurately and steady. I typically see 185 degrees on highway and a bit higher up to around 200 in idle/stop and go traffic