BMW 2003 problem

Has anyone had a problem that their BMW is sluggish when starting from idle and consinues to be sluggish until 30-40mph? Also, once I make it to 50mph, it begins to be sluggish, all the while the car is shaking form idle to any speed. In addiiton, the car sounds like a beater with vibrations under the gas pedal. Anyone have these issues?

The dealership says it is a muffler problem or a cracked pipe.