Hello i have a 2000 Toyota Avalon XLS that i picked up from a salvage auction a couple years ago. 175000 Miles.  Its been a great car after simply replacing the rear steel bumper under the plastic in the rear.   But on to the issue.  The Brakes seem inconsistent sometimes(dont worry its minor annoyment).  The main issue is that i feel is sometimes when i come to a stop the brake pedal seem to just drop a inch and then be firm and be fine.  Even rarer is sometimes it doesn't feel like there is much boost assist to the braking.  Its not often but it is definitely different than my wife 2009 Camry braking which almost feels overpowered in comparison.   When i looked into the Toyota service history i did notice that it was often checked at the dealer for the floormat interfering with the brakes,  not sure if it was just a overly worried owner or from what i suspect is that this has been going on for a while. 

Ive follow previous scotty videos about testing the booster and brake cylinder but no obvious failure was apparent.  No codes or leaks going on.  I did replace the rotors and pads but that did not change the behavior.  I have checked the hose and check valve to the booster.  ABS seems fine.  Its not the floormat  either.

If i were to lean to a issue that its a intermittent issue in the brake booster.     What do you think?