I'm a noobi to turbos. Just had an engine replacement and turbo worked slightly could feel it kick in then wouldn't feel it after 3rd gear. sometimes it would work flawlessly in 1st and 2nd gear then feel it slightly in the rest of the gears. And now drove it on highway for like 25 min and I'll accelerate and it starts to jerk a tad and cel flashes I'll release accelerator and it stops as long as I don't hammer it but then I'll try it again and no boost just motor need some help from y'all veteran Audi owners

 

Oh and I also did a scan and the code popped up was p0300 multi miss fire could this cause the malfunction?