Code 2B64, manifold code?

So, the code 2B64 means there is air leaking into the intake manifold that is not passing through the air meter, it will probably be the intake is cracked which is common or you have a gasket or hose leak. Check the air intake tube for leak, use a flashlight and really go over the plastic intake then if you can't find it test the engine cold by following this guide:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Here are some key points to look for a leak

Thanks. I will do a smoke test. Could a valve cover gasket leak cause this?

yes, it could, please check it for cracks as well.