A4 B7 2.0TFSI, No power and PCV issues

[Svengard]

Hi all, 

A few month ago I bought a 2004 A4 B7 2.0TFSI, 111k on the clock and a service history up to 105k.

The problem is that the car is leaking power. Before I got the car the PCV valve was replace from a Audi garage (April 18), but as soon as I open the oil cap or pull out the oil stick, the engine is sucking air and starts to idling very bad. I am not sure if they replaced the tubes too. Last weekend I checked the connection of the tubes and even took out the valve to have a look, but to be honest I was not sure what to look for and I know a bad PCV could cause the systems. 

The car shows no errors and no lights are on, on the dash. 

I also heard that the diverter valve like to go bad or at least the old versions of it. I haven't checked that yet. That could be the issue for the lack of power, but not the sucking air issue. 

Does someone has any tips what the issue could be or point me in the right direction?

Thanks

[ImJB]

replace or blank the pcv, replace the dv . What’s the worse that could happen