Logging 2554 and 2764 code

Hi guys, it's been a while since I posted last time.
Having this intermediate issue with high exhaust gas pressure on my ISX15ST. Installed new sensor, didn't help. I ran a regen and it seems to clean dpf nicely with good Temps and all but it still does fail due to VG being below minimum and turbocharger above maximum. I'm not sure if VG is not responding properly and it is over spooling turbo causing high exhaust gas pressure or there's a leak in the intake system (haven't pressurized CAC yet)
The symptoms are coming and going, when codes are active I get engine derate. Thinking of wiring issue?
Has anyone experienced such symptoms and could possibly point me in the right direction.
Thank you, Jacob

 

2554 and 2764 Resolved however, regens complete but with failed result.
After unsuccessful regens this morning decided to look closely at the sensors and 3 out of 4 (except Imap) been replaced recently including exhaust gas pressure sensor. Returned to Insite and noticed that every time now when I wanted to run a test involving regen, as soon as boost hit designated levels it would throw Cel and kick me out it. FYI, day earlier had no such issues, I'm thinking weird huh? This behavior led me to believe that I may have a wiring problem, guess what I have discovered lol!
Someone has already messed with Exhaust gas pressure sensor wiring (see picture) the white signal wire was cut off before the plug, it was substituted by yellow wire that was ran inside silver 1/4 in air line. I began to follow it and it took me all the way to the top ECM plug where it originated, so there was my aha moment. Initially I thought that this is going to be a mess but at the end it turned out to be issue relating to crappy contact by EGPS sensor prong and the plug. Cleaned both the plug and the 3 sensor prongs, applied some aluminum antisize lubricant, twisted the prongs ever so slightly also since I was there I cleaned up the supply line for EGPS which wasn't clogged, I've removed a little bit of soot from the manifold body where the sensor is located. Perform few tests and ran around the block and no code, so I think I may be alright with getting rid of codes 2554 & 2764 however as I mentioned earlier I still have failed regen with no codes due to turbo over spool is what it said in the messages after regen process has stopped (see additional pics)

My question to you professionals is:
Is 84,000 turbo rpm too high during a regen, it was the highest speed registered (see picture). Is there a possibility that turbo speed sensor is giving faulty readings back to ECM thus my regen fails?
I did VG test and it passed also, I followed a turbo speed readings (percentage) and it matched desired to actual. Truck completes regen as soot levels afterwards is in the range 5%

Looking for some opinions, thanks everyone
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Can you shed some light on the procedure? Not familiar with diesel force although I can Google it, lol