I recently picked up a 15 Golf r with a dsg. The car is stage 2 according to the previous owner. It’s got a unitronic downpipe, racing line intake, and stage 2 tune. I’ve been having this issue where when I am accelerating on the highway, usually in 4th or 5th gear around 80+mph the car just cuts all power. The car still down shifts when I’m pulling over, but once I come to a stop the car just shakes untill I shut it off. I turn the car back on and it’s like nothing happened. I took it to the dealership to see if they could find the issue, all they said is that I could be a problem with the tune. Any help is greatly appreciated