Brake problem on corolla

Are the calipers able to move back an forth on their pins? Is there grease on the rotor surfaces or brake fluid on the drums? You used the term "rotor" ... as in ONE rotor. Did you replace both on the front axle or did you make a typo? ;^)

The rough and ready method described in manuals sometimes and used by mechanics is to apply pressure to your brake pedal, then start the car (pump the pedal before starting car to use all avail vac). The booster will pull the pedal down slightly (varies, but at least 1/4 in). The in-linevlave can fail and allow stored vacuum (for idle periods) to dissapate into the intake manifold.

The compensating air-filter can clog restricting diaphragm movement or the diaphragm can rupture (in which case it will fail the firt test and the test you have mentioned plus the engine may develop a miss on the cylinder/s closest the vac-port)

Jason