Hello, im having trouble with my turbo. Any help would be appreciated.

It all started few months ago, when suddenly on highway, cruise control switched off and check engine light came on. Boost dissapeared and it didn't go past 2200-2300 RPM. Tried restarting the engine when driving, few moments it was all OK then again same issue. Plugged in VCDS and car throw me a code of N75 valve and overboosting. Changed N75 valve to new one, checked all vacuum hoses and then took the turbo off, turbo was ok. It was all clean, flaps were moving nicely and no excessive clearance. Actuator hold vacuum nicely. Put it all together. Went for a spin, it was better but still hesitating. After few hours of driving again limp mode. Tried restarting engine on drive. Boost came back for a moment and then again dissapeared. And when it now dissapeared, pushing the gas pedal a big plumes of black smoke came from exhaust and rattle noise from turbo. Plugged in again VCDS. Threw me an error of Boost pressure regulator and EGR valve. Changed it, also looked up for the intercooler and all intercooler pipes. No leaks on pipes. Cleaned EGR system. Nothing, still the same. Tried blanking the EGR and EGR cooler, cleaned MAF sensor, nothing. When i take vacuum hose off from turbo actuator or from the intake manifold flap actuator, engine works nicely, but when i put it back, strange noise comes from turbo. Any suggestions what should i do next?