Why does my 2008 Chevy impala jerk while driving on 2008 Chevrolet Impala

The car jerks but smooths out when gas pedal is applied. Bad gas or need plugs?? It has 79000 miles and Chevy says it doesn't need a tune up.

Asked by for the 2008 Chevrolet Impala
plugs would be a good start as it is time according to the mileage.