Feeling a loping in the engine while driving. on 2011 Buick Enclave

It almost feels like when you have the cruise control on and it doesn't quite catch up (like on a hill), but this is happening with no cruise control on, and it has happened on level streets at around 20-30 mph.

Asked by for the 2011 Buick Enclave
2011, should still be under warranty. Take to the dealership.