I am searching for vacuum leaks. I have traced most of the small lines and repaired old tubes. Someone has plugged the metal line by the non functioning cruise control bellows. The other side of metal hose on the passenger side is open and the rubber vacuum hose not attached. I have been trying to figure out where that rubber hose connected to the intake in case it is open and causing problems. I think it connected to a fitting directly down from the fitting the distributor vacuum regulator connects to the intake manifold. There was a 1" piece of hose dangling there. The arrow in the photo indicates it. Am I correct? It definitely has vacuum when running. Here is what is making me nervous. When I removed the old gummed up piece of tube, oil started dripping out, not pouring, maybe 5 drops. Any advice? I have been experiencing gasping and stuttering at high RPM's specifically stepping on it and downshift at 70 mph, she will not shift to 3rd unless I let off. And indeed will gradually lose power unless I decelerate slightly. I just cleaned the tanks and replaced the main fuel filter as well as the 2 pre-fuel pump filters. I am getting 31 psi at the rail idling, if I gun the throttle it leaps to 39 psi. The search turned to vacuum leaks. picture taken from under right side of car pointed up at the bottom of the intake manifold, right side of picture is toward the firewall. Thank you for any help!

 

After some more surfing, and reading posts on oil in the manifold, It looks like on series 3 cars, that port is just a plug, probably for draining that oil! Where then does the cruise control vacuum tube connect to the engine?

 

My 84 EFI XJ6 Auto, has it going to a vertical tube just aft of the throttle body (inboard - aft corner) . It appears to be the inboard mounting bolt to the auto-kick-down cable Bracket. It is 4 inches directly below where the #1 fuel injector hose attached to the fuel rail. Rgds David