2007 4Runner brake issue

[Epic Ed]

I recently purchased a 2007 4Runner -- 4WD, Sport Edition with 123K on the OD. I'm getting some feedback from the brake pedal on occasion during normal braking at in-town traffic speeds (45 mph and under). It feels like the ABS is kicking in briefly but I get no ABS lights on the dashboard. The brake pedal shudders/jitters 1-3 times very quickly and then braking returns to normal. I've checked the brake fluid levels and they are at the high fill line. I just had the vehicle inspected (Uber driver) and the front brake pads and rotors are new (confirmed what the dealership told me when purchased). I'm not sure about the calipers, but brake pad wear looks to be even at this pint, so I don't think I have a caliper issue(not eliminating this as the issue, but nothing points to calipers upon initial inspection).

Any thoughts or ideas about what may be causing this? Master cylinder? Brake booster? Faulty ABS sensor?

 

[riceandpho]

i would atleast flush out the old fluid and put new fluid in, im using dot 4 and it seems better than my 3 year old dot 3.