X plate 2.0 cabriolet couple of issues

[plugy]

On the drive to work tonight I actually noticed that lift off results in engine movement. So.. I wonder if the jerking at lower speeds is due to a fubard mount or shaft?. I.E accelerate quickly and it jerks at 1500rpm or lower. Accelerate the same way at 2k rpm and it doesn't do it. If it was a missfire or otherwise it would do it anywhere in the Rev range presumably. So perhaps it's a mount or shaft?... would this make more sense

Thanks
Rob