Either Transmission sticking or Im dying

[Callmecaam]

I have recent bought a BMW 530D E60 from 2003 pre LCI with 182,000 miles from a buddy who was leaving. I'm now driving it and have notice a weird thing that happens when driving in lower speeds and high speeds but its more obvious during lower speeds, it seems to lack power as if the turbo doesn't work so I replaced the turbo. Still didn't fix anything even with my foot to the floor the car is just sluggish and has small burst of turbo pull then it s off i don't know what to do.