The vac line for the AC and the guage has a "y" connection just behind the brake booster, so check that.

However, I believe you have a large vac leak at idle, most likely the idle control valve hoses.

Pull off the air filter housing complete (three 10 mm nuts, on on the side next to the fender, one front, on rear on the engine side). The idle valve is about half the size of a coke can, two wire connector and two large rubber hoses, one to the fuel distributor and the other to the intake (that end also holds the cold start valve). LIkely they are rock hard and loose on the valve. Replace them -- the one to the fuel distributor is easy, the other is a huge PITA (took both my brother and me on that one, one to guide, one to push).

Replace all the rubber connectors on the vac lines, too -- they are all shot as well. This will fix the vac leak, repair the idle, and cure the throttle lag, since all are a result of the lean mixture from vac leaks.

Did all this on the TE right after I bought it.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!