Engine runs rough

Hello,

Vacuum leak can occur from any of the vacuum hoses. It can also be from leaking intake gasket.
If you have already checked the hoses, it will be a good idea to check if the intake gasket is leaking.
With the engine at idle, spray carburetor cleaner into the base of the manifold. If there is a leak the engine will react to the chemical and will idle higher, then it will go back down after the chemical gets burnt off.

Here is a helpful guide:

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

Also it might be good idea to clean out the throttle body as dirty and debris in the throttle body can create idling or engine running rough issues.

https://www.2carpros.com/articles/throttle-actuator-service

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.