brake problem

You might need to adjust the rear brakes. This is common when replacing master as old probably did not actuate them properly. And you probably still have air in the system. When you have vacuum there is enough pressure to compress the air.

Try loosening a bleeder then put your finger over it then have some one pump the brakes. I start with closest to master and work my way back. This is opposite of what is taught but it works better.
Air finds its way to high spots in the brake lines and sometimes is a bieotch to get out.

A friend of mine is a Toyota Master Tech and he uses a small pump up yard sprayer and pressure bleeds up from wheel cyl. Empties master then as soon as bubbles stop he goes to next bleeder. Does complete bleed job alone in less than 30 mins with less than a quart of brake fluid.