I have checked all the vacuum lines and all seem fine - except a vacuum line that comes from a small barrel shaped unit next to the fuel distributor, which has a gas line in and then a gas line line out to the fuel distributor. I thought it had a steel nipple to connect the vac line which goes to the valve cover and then air cleaner but I was wrong, it has a rubber tube that goes into the unit which I yanked out and now can't properly re-insert. Do you have any idea what this little unit does?

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1986 300E