Cranky noise present during acceleration at 2000 rpm

The car runs rough, especially if it is cold. It is loud and it hesitates. Others that have driven it say it feels like it is going to throw a rod (not sure what that means to them). I have brought the car to the dealer for this problem three times. They simply state "problem does not repeat itself". I am practically deaf and not only can I feel the roughness, I can hear it as well. As with my oil consumption problem, I am dismissed by the sales department personnel.