vacuum line toward firewall.
I cannot find vacuum diagram
thanks.

 

It goes to the place where all things go.
Be more specific for crying out loud.

 

Rearmost point of intake manifold (above rear valve cover, toward firewall) has a vacuum port. I plugged it (it was broken)couple months ago, when I bought the car. I have ALLDATA program, but it doesn't have vacuum diagram.

 

 

OP the diagram you posted (rubbery thing, very easy to pull off) connects to the back of the fuel rail
If you pull it off the rail you will have to take the intake off to get it back on
It must be used to regulate fuel pressure based on vacuum but I cannot think why anything like this would be necessary on a vehicle with EFI