Hi, im a proud owner of an 190e 1.8 automatic, and i need some help!

At normal driving, the car jerks, kind of chases the rpms.

A friend of mine changes the plugs and fuelfilter, but that did not help.
When the plugs got changed, he mentioned they were a bit dry.

Could this have anything to do with the jerking, the car might not get enough fuel? If so, is there a way i could manually adjust this?