04" 330i stalling, loss of power and rattling noise

The rattling noise under the car could be a muffler baffle come loose and restricting the exhaust. This will cause loss of power and high heat conditions under the car and in the exhaust of the engine. The check engine light indicates that the computer has detected a malfunction in the engine/transmission control system and has diagnostic codes and data stored which would be essential in diagnosing the problem. A technician with a scanner can access the diagnostic codes and data and then be able to give you a diagnosis. If you can't afford to check it out now, don't drive it. You are asking for trouble if you do, and as you are aware, a German car couldn't care less what your finances are like. They are expensive to buy, expensive to maintain, and very expensive to repair so don't break anything.. If you want to find a Beemer specialist, here's our directory link for you: https://repairpal.com/bmw-repair-in-hartford-connecticut