This doesn't happen every single time I start my car but, I start my car and when it idles into the proper idling spot it makes like a rattling noise, it's only when the idle drops down and it's gone after I say 2 seconds and my car runs fine after that, this is a new issue i've found it's only started maybe a few weeks ago now but nothing about my car has acted up, I don't think it's my motor mounts since its not all the time, and i'm not sure what it could be.
just checked some videos on youtube sounds like the timing chain but it's a brief sound for 2 seconds and not constant.