P1415 Issues not able to solve although testing done by 2 mech

Question

I have a 2006 BMW 525i . After replacing serpentine belt and an upper radiator hose, the car lit the CEL with a P1415. After a negative smoke testing Mech suggested to replace CCV valve. After that did not fix issue He replaced MAF sensor. That also did not fix the issue. So he told me to have an electrical shop look at the connector at the MAF or the Computer. P1415 was the only code scanned. I drove the car for a week and now I have 2 more code P0171 & P0174 so definitely there is a leak?

Another mech diagnosis wants to repair all the oil leak first and then see where the leak is. But if the smoke test did not show any leaks and the crankcase Valve, along with the 3 hoses were replaced, the MAF was replaced but problem persist.... is there any other valve I can look at ?

Car was running great prior to replacing belt......

Jack