It is 2012 Skoda Octavia 1.4 TSI DSG7. When slow turns (i.e. u turns), car starts to shake like it is about to stall. The rpm is low but stable, engine sounds under-rpm, tiny vibration on steering wheel and all effects are intensified if you push the throttle more and more. So is it transmission/clutch problem, front group of steering/suspension unit or something else?
If you are turning the wheel all the way (left or right) until it stops, this is called cramping the steering. What happens is, when you get it all the way over to one side and hold it there, the rack and pinion is telling the hydraulic fluid to continue to push the steering over to that side, but the steering mechanism cannot do it because it cannot go any further. This sends pressure waves back through the hydraulic system which causes the pump to stall momentarily. When this happens, the pump slows the engine down.
To counter this ... don't cramp your steering. Run steering wheel right up to the end of where it can turn the wheels and don't go any further. You will not get the wheels to turn in that direction any further anyway, so you are causing yourself an issue which doesn't need to happen.
From the symptoms, I think the power steering belt will be slipping under the load at low engine speed.