I know this was almost two months ago, but I finally got it figured out! I have been driving it reasonably since then and i haven't had any issues. But i noticed an oil leak and decided it was time to take it in. Let's just say the engine should be good for quite sometime *knock on wood*. Here's the list of things replaced/fixed: Intake manifold gaskets, valve cover gaskets, engine mounts, transmission mount, torque strut mounts, thermostat, and PCV valve. The knocking noise that I couldn't figure out a couple months ago was from broken engine mounts allowing the engine to torque too much. But hopefully the monte is all set for a while

 

A chevy truck I had years ago had a weird noise when cornering and it was a rear transmission mount. glad you got it all fixed up.