2006 Suzuki Forenza that has a motor tap that needs to be fixed. Otherwise great

Cosmetically the car is in great shape (except a ding in the rear bumper) Transmission runs good. and the engine seems to be in good shape other than the motor having a tap that seems to cause it to run rough. The car had run low on oil and seemed to do something to it. It was suggested to us that it was either the oil pump or worst case the heads need to be redone. If your mechanically inclined or have a friend that is. this could be a great deal.