2015 TSI Golf drivetrain disconnects???

Please bear with me on this; I drove my TSI for 1 hour in bumper to bumper traffic, then one hour highway speeds. Floored car to passing gear Car went to 6500 RPM and then seemed to disconnect engine from drive train resulting in very hard loss of power jarring passengers. I let up on gas, tried again "BAM" jarred passengers incl. driver, as if drive train disengaged. Drove rest of trip in slow lane at 65 mph gradual acceleration. After 3 hours of car not driven. I drove home could not simulate problem. Dealer said; could not simulate problem, no codes. Next day drove 5 hours to Va. no problem. Next day drove 4 hours and floored car in passing lane and it quit at 4200 rpm, backed off, floored again 4500 rpm BAM disengaged and slowed abruptly as again, let off gas ran ok, floored gas again, 5500 rpm BAM disengaged slowing abruptly, jarring passengers, loss of power lunge. Let off gas. Seems if car is driven for awhile problem appears. Left car off for 2 hours and drove home. No Problem.
Dealer said; If I can't simulate it I can't fix it. Really? No diagnostic service? vehicle has 9920 miles. BP gas. I'm guessing throttle body failure? Please help

2015 TSI Golf drivetrain disconnects???