Noticed that my engine started having some issues with rough idling when cold. Checked everything to include the EGR and changed the fuel filter. One day attempted to clean the throttle body and the :air intake manifold with throttle cleaner and noticed that the intake elbow that attaches to the throttle body was torn. It looks like the metal brace clipped it and it had several small cracks.Apparently air was leaking in at cold temperatures and it corrected itself after the rubber heated up and the cracks expanded and sealed. After the engine reached operating temperature the rough idling smoothed out a bit but not totally.I ordered a new intake elbow and the problem is fixed.