Octavia 2 boost issues

Hey guys

Just a quick one for ages I have been getting fault codes to do with intermittent boost problems, changed the MAP sensor and MAF sensor and it's boosting again for a few days it was acting like the system was choked the car was juddery then a big puff of black smoke and the car would shoot off, I thought with the turbo not having been working that there may have been a bit of a carbon build up but it's been a week and I've used a couple fuel treatments and it's still acting the same all juddery and then big puff of black smoke then smooth running

There are no fault codes now, but there is a difference between boost pressure actual and boost specified could this be a fault MAP sensor? I Went a quick drive with VCDS plugged in and the boost actual stays at 908mbar but the specified raises based on acceleration, the car drives great other than this juddering and splutter of black smoke

Any info would be greatly appreciated