Just bought a 04 A4 Quattro for my son. Sounds like the diverter valve is rattling bad when coming off throttle. Followed the vacuum line to test it and found what appears to be something missing. Under the intake is a plate that has one sensor with connector and vacuum line from DV terminates to it. Another connector is hanging loose and a larger vacuum line appears to be capped....what am I seeing here?

Note capped line with green mark and unplugged green connector