Im dealing with the same issue a-lot of Xterra owners have, Squishy Brakes. So far I have changed all 4 rotors, and all 4 brake pads. Just got it back from the mechanic where he power bled my brakes and he said there was definitely some air in the lines that he got out. Its braking a little better, but nothing to right home about. He also checked all my suspension and said everything was in great condition. The next step that I saw on here and Reddit was to take it down a dirty road and engage ABS a few times and it worked for a-lot of folks. Well I did just that, took it down a dirt road and sped up to 40-50mph and slammed on the brakes, the only problem was, the ABS light NEVER turned on, flashed or anything. Is this a problem? Im so lost at this point...