I have a second hand Suzuki Swift GL 2006 for two months now. When I got the car after a few weeks I noticed the brake pedal was sinking to the floor and got the master cylinder replaced it was fine for a couple of weeks but it started happening again. Bled the brakes and was fine again for a while but after another week or two it happened again were the brakes were bled again with the same effect. I brought the car to a different mechanic and he said there was water in the brake fluid so he completely changed it and the pedal is still a bit soft but he said it could take a little time for the new fluid to go through the ABS. The brakes have always been perfect and stopped the car well, I just noticed the creeping pedal while I kept my foot on the brake at a stop sign or in traffic for example. Also if I have my foot on the brakes and stopped in neutral the idle revs decrease and return to normal when I come off the pedal. I don’t think there are any problems with the booster but what do you think of this slight rev drop when I am on the brake? I am at a loss with it and not too worried as the brakes are perfect other than that I would just like to figure it out. Could it be a faulty ABS pump?