http://www.mbclub.co.uk/
I'm pretty certain yours is not vacuum controlled. It is too new. Is the check engine light lit up?
The shutoff valve should be an electrohydralic solenoid located on the side of the IP. It is a black plastic valve with fuel lines attached. When you say you replaced the shut off valve are you referring to a "push button" type kill switch located on top of the fuel filter housing or the aforementioned solenoid?