VXOC Astra-J/GTC

Hey guys,

Noticed something alittle odd on my 1.7 Astra GTC 62 plate.

I was letting the car idle stationary and was hold the revs at certain ranged.to get the engine warmed up.

I noticed when the rev counter hit approx 1500rpm - 2000rpm I could feelnthe car shaking abit, but then below or above the rev range it would smooth out and be completely normal?

Any ideas on what it could be?

Thanks in advance.

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