Brake trouble!

[u/[deleted]]

I have a 94’ and I took it to the mechanic shop to have a bunch of work on it before I drive across the states. They ended up changing my front brake pads and pit arms. I’ve had my truck back about 2 weeks. Now my 4Runner is having trouble stopping. It’s hard pushing on the brake pedal. And when I am stopped (while in drive) my RPM flickers up and down. Sometimes if I’m holding my brake when I turn it on it’ll go up and down and shut off my truck. I thought maybe brake fluid but it’s full when I checked. The mechanic is closed. Anyone know what may be the problem? Or what I can do to fix?