2007 Mitsubishi Grandis Brake Padel Going Down Fully

Normally for my car Brake pedal was not going down, but when in emergency the brake was applied and ABS was activated the pedal was going full down by making "Grrrrr" sound and when releasing pedal it is coming "chooon" Sound like air. So This sund comes whenever brake was applied. But after few days the problems gets solved but again appears when brake is pressed in emergency.
For few days now the pedal is always going down and that problem is not getting reset as it was reseting after few days
Now I have changed the brake Master Cylinder But problem Remains Same.
As per technician this sound appears from ABS Modulator.
Please give better suggestion to clear this matter

Regards,

yasir