I will provide an honest answer. I trust this will be appreciated on a Sunday. Please remember that a low rating PUNISHES me honest and that I receive nothing time until a positive rating is clicked.
I would start by looking possible plugged cat or a failed turbo.
a live diagnostic (not just a fault scan) should be able to reveal more information about what is going on (this type of diagnostic can read out all inputs and outputs from the engine management system in real time)
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit answer, thank you. Best wishes with your vehicle.