Requesting help for troubleshooting codes

[Ngkx535d]

So I have the following codes:

452A - Particulate Filter system
478F - low press exhaust gas recirculationvalve, plausible.
47C9 - low pressure exhaust gas actuator pod control.
4D6C - exhaust gas temp sensor before particle filter.

Problem is, I get no boost or power past 3k RPM, and when I attempt to push past 3k RPM, I get an engine malfunction/reduce power message.

I’m not worried about the 452A code as I monitor regeneration via Carley and the system operates as advertised (I figured out months ago by reading this forum to replace the thermostat).
I removed the manifold and cleaned it out (wasn’t really dirty) and placed everything back together today. Still the same issues.

I don’t want to throw parts at it, but I ordered a pressure converter after reading various posts/threads on this forum (part number 11747805391) but I’m curious to know if this is a good start.

Also - can somebody tell me where this is located lol???

Thanks for any help.
-Nick

[Ngkx535d]

Update-
I changed out the pressure converter and the vehicle operated fine.
I used the vehicle for a vacation trip (800 miles; round trip) and literally went into limp mode as soon as I got back home. This happened when I was going up a very steep hill on the freeway in attempt to pass another vehicle (wide open throttle, ~95mph).
Now I have:

-429A “ Boost Pressure Control Low Pressure Stage, Deviation”.

The vehicle is in/out of limp mode and driving it is almost impossible because if I give it any more gas than ‘grandma speed’, the warning message appears followed by the obvious loss of power.
I downloaded ISTA+ and finally got it working but wanted to see if anyone can point me in the direction of how to perform test(s) in ISTA (throttle body, EGRs, etc) to help eliminate what is not causing this issue.

Besides performing anything in ISTA, I plan to take everything apart again and check for anything loos, connectors not plugged in, or damaged air lines. I also plan to remove the lower charge hose and replace the seals as I notice ALOT of oil weeping out the lower charger pipe leaving the oil cooler, at the turbo side.

So, can someone help me out with ISTA and/or provide suggestions of what replace/check to get my car back to normal lol?

Thanks for any suggestions, I will continue to update this thread.