You have a vacuum leak.
First off, you can use the emergency shut off on top of the engine to kill the fuel supply. If you don't see it refer to your owners manual.
Driving any car with disk brakes and no vaccum assist is very scary and worse, can be dangerous. I would suggest not driving the vehicle until you solve this problem.
Next, you need to determine why you are not getting vacuum to both your brake booster and your fuel injection pump. I would guess that you might have a bad vacuum pump. It can see it by looking at the engine (radiator to your stomach) it will be on the right side (left side of the engine). You will see a white tube about 1/2 inch, if I recall correctly, running from the pump to your brake booster.
If you do a search in the Diesel section using key words such as vaccum and brakes, you should turn up quite a few postings.
Keep us posted,
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