OK still along the same line as I was saying a VAC HOSE WOULD NOT CAUSE THE CODE YOU ARE HAVING. Also never seen a single gasket system for each intake port go bad. Its just a rubber oring style for each port so kinda odd that one just out of the blue fail. Now if the intake was removed yeah I can see that or oil leak around the area then yeah I can see that to. But you did just as I asked you made him check for the correct issue and not a vac hose like you were trying to push for.
A throttle body cleaner spraying in the area would have been just as effective in locating an issue such as that.

 

I did not tell my mechanic what to do. He checked for the vacuum leak and found that air was leaking from the manifold casket causing extra air to have bank one run lean. While the manifold is off he will change both caskets and check the o rings and replace as needed.

Thanks for help, Stay Safe