Best to take it to the diesel forum, this is all covered extensively over there.

The vacuum pump original design (smooth front cover vs the later with bolt heads on the cover) is considered by many to be a bad design that can without notice drop bearings into the timing chain and destroy the engine. Search the diesel forum for more info.

The EGR and ARV are not critical for the operation of your year engine, again covered on the Diesel forum, but the standard response is to buy an F vacuum-splitter to replace the 5-way in front of the engine and eliminate the ARV, EGR, and all associated plumbing on the exhaust side of the engine.

EGR blocking plates were being made by a member, not sure if they still are. Nice look, probably should get some some day for my engine.

Vacuum troubleshooting is tricky as you might already know. Best to isolate circuits and test for vacuum-holding capacity one circuit at a time. The most common vacuum problem is the (brown hose) HVAC (ACC) system. If you have air-conditioning coming through your defrost vents at all times, can't get cold air through the center dash vent, or can't get heat out of the footwell vents, these are all signs of bad vacuum actuators (pods) in your system which are leaking air (vacuum). You can try disconnecting/pugging the brown line to the dash to see if it will alleviate your problem.

Thinkng, ... I believe it is brown, or is that the shut-off to the ignition switch/IP? Which brings up another question: Does the engine shut down immediately when you turn off the key? If not, an indicator of low vacuum. That line comes from a Tee connection on the brake-vacuum check valve (separate feed on the vacuum pump). If it is good, probably a good vacuum pump.

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Gone to the dark side

- Jeff