Soft brake

99 V6 AT, it’s been running fine since I replaced the alternator brushes. Today I noticed the brake pedal is softer than usual. Checked the pads, bleed the caliper, and the pedal still soft. Another interesting thing is I keep getting air when I bleed the calipers. I must’ve bleed the calipers 10x and still get air.
Wonder if my master cyclinder or booster is bad?

also, if I pump the brake and then stop, then it’s perfectly fine. But if I have to do a panic/stop without pump then the pedal would act like it’ll go thru the floor

 

Sounds like your master cylinder has an internal leak. Take it off and look it over. Probably has fluid leaking around the piston and thats how air is getting in.