Engine noise cold start

Hi everyone I have a 2011 mazda 3 2.0l
start it cold it has a loud rattle type of noise from the front/top of the engine, then it goes away after it warms up. It's only does it in gear When you put it in park it sounds fine, when driving and you let of the gas it sounds fine. Then as the car warms up it completely goes away. Any ideas?
I was researching and found some threads regarding the VTCS system, and it creates this condition when the vehicle is cold.
Any idea?
My oil and filter are good