These are photos from a '94, 6 liter (litre). I realize two different engines, but this looks similar to what you've got.

First picture is a "T" junction on the (US) driver's side, front end.
Second is where it makes the connection to a bellows (?), looking aft.
Last one is an overview. Green is the starting point, Red is the end.

 

WTH--Found where it goes"no where" the other end went under ac compressor and was smashed between wiring harness and ac compressor so when I sucked on the end of it could not draw air therefore I thought it was connected somewhere. The other end came up to the inside of first intake manifold port on driver side was not connected to anything,probably a hose rerouted and PO just left it there, took a lot of pulling to get it out hose was squished flat in the middle.

The hose running to cruise is there and plugged into the blue thingy Doug mentioned, I took it off of that point sucked on it and air flowed easy no vacuum at all. Is the rubber accordian bellow just a dust cover, it is not sealed.
Cruise control does not work.

From the looks of it spark plugs are a PITA to change.

 

The accordion is the bellows for the cruise control and it must be sealed to hold the vacuum. Check out the various posts on cruise control for the fixes.

 

Changed the modulator valve it shifts now, before it went bad it was smooth shifting now it is a snap shift. The old,old mod valves had an adjustment screw this one does not.

The bellow is not fitted on the metal disk around the bottom.

 

Doug,
That's awesome!! You should add "AFA certified" to your signature.

 

Can someone post a good pic of the bellow of the end facing the firewall ?

Can bellow be repaired maybe put some silicone where rubber meets metal ?

 

Can my very large accordian bellow be replaced with one like yours, looks like the one on my 98 Chevrolet p/u.

 

IMHO the easiest way to fix this permanently is to replace the vacuum unit with an aftermarket servo unit for a couple of hundred bucks. As your XJS is a later model it will have the electronic speedo so integrating the aftermarket CC is easy.

 

Yes, it's a common fix....and sometimes that's all it takes to bring a dead cruise control back to life.

More in-depth repairs explaine here:

Cruise Control


Cheers
DD