2006 3 2.0 rough idle/check engine light
 

I've got a 2006 Mazda 3i that idles super rough and vibrates a lot. It's throwing a check engine light, something about the intake manifold. I took it to a dealer and they said the intake manifold was damaged and needed to be replaced and they wanted $1500 to do it. I bought a new intake manifold and can change it myself but I'm wondering if this is the most likely solution. Does anyone have experience removing the intake manifold on a 2.0?

Side note, the engine is super loud (clicking sound), I wonder if it's a worn out pully/tensioner? Anyone have any experience with this?