E=MC^2

Hey guys, I have a 1993 190e 2.3 automatic with 106k miles. The brake pedal is soft, when I slam the brakes it rolls to a stop. I bled all the calipers and put in a new master hoping it was that not the booster... It is the same all I can think of now is either a bad booster or serious vac leak?

How can I test the booster/ what else could cause a soft pedal?

Thanks
-Brian