Rattling Noise Possibly Engine

Just today I started getting a rattling noise while my engine is running. It was not doing this when I left for work (a 60 mile drive). I have had engine codes for Cylinder Misfires and the Exhaust Manifold since getting the car. Does anyone have any idea what may be causing this, can it be related to exhaust manifold and cylinder misfires? It can still be heard when driving but the car is driving fine. I have an appointment with a mechanic for Wednesday, I just hope it makes it until then.

Did you check the timing belt tensioner? Wheel bearing and cv joints can produce a rattling noise also.