Throttle pedal vibration over bumpy surface

[p1tse]

Picked up a b6 audi 2004 s4 recently

Had a service and picked up splitting front upper arm gaiters so not sure if these would cause such a symptom

But over uneven bumpy surface I can feel the throttle pedal movement/vibration (feeling its moving a little left-right/right-left)
But when moving along or at idle there's no movement from pedal

Could it be the upper arms splitting gaiters or something else to check/ask garage?
Thanks