How much vacuum should 240d have?
 

Wondering if someone can tell me how much vacuume my Mercedes 240D should have and, if the following sounds troubling or fine;
Car shuts off.:)
But, vacuume gauge reads about 20-24 when tested at idle speed from brake booster hose, however when I open the throttle the preasure decreases to about 15.:(
Also, sometimes when hard braking the brakes go soft and I just push harder and seemes to work but can be alarming.
Also, and this is the weird on, Car suffer's from low power sometimes (too much blow by) but, say I'm at a stop light, I drop into neutral and pump the brake (disipating vacuum) then when put into drive the car takes of like the beautiful machine it wants to be, but whitout pumping brake can be quite sluggish.
Thoughts? Thanks,