CM871 losing power

[victory26]

Hello everybody! I do own an ISX CM871 2009, and I am experiencing a problem for awhile , the engine its losing its power after ecm reprogramming. It's currently running on maybe mm? not sure? . It will run strong for about 4000 mi then the power will decrease to about 70% . I had it reprogrammed a few times and it does the same thing after a while. I did check turbo and all clamps for boost leak and everything looks fine. I did replace the imap sensor and exhaust back pressure sensor and havent noticed any changes. I also had replaced all injectors 3 months ago. The engine runs smooth. There is no active codes. Boost will get to a maximum of 32psi and the exhaust temperature it will be between 670-750° driving 62-65mph. If anybody had such a problem please tell me how you got it fixed. I did take it to 3 different shops and no one knows what's wrong with it. Thank you!