It almost sounds like you used up your available vacuum by depressing the brake pedal several times before trying to actually stop. Check your vacuum source, the vacuum pump, for proper function. Using a vacuum gauge, it should be pulling something like 22" HG. Also, check the big vacuum line that runs from the vacuum pump to the brake booster, make sure it has no obvious holes/leaks. There may also be a check valve involved
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.