I've used Textar pads front and rear on my 300TE, and old 260E for a good number of miles. Its definitely not the pads.

Since the pads wore within 95% of each other, I think the odds that the calipers BOTH sticking at the exact same time is extremely slim.

BatteredBenz -- The master cylinder makes sense. Is there a way I can test if the M/S is the issue?

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k