Refurbished turbo fail?

Hello,

2006 1.8 TDCI (125HP). A refurbished turbo was put on it (+oil and filter, +gasket), electronics remained the same (old turbo ate the oil and hummed). When accelerating, it pulls in from low revs around 1700 revs for a moment, as if it "misses". After that, it accelerates normally. It didn't do that with the old turbo (it didn't jerk). It didn't touch anything else.
After stopping, a sound comes from the engine compartment. As if the air is escaping from somewhere."farting sound" My question is, can the turbo handle the engine like this (geometry adjustment problems?), Has anyone had this or a similar problem? Maybe go the other way?
Thanks!