What causes brakes to pulse or shake when applied? on 2003 Cadillac DeVille

I've had the rotors ground twice with no lasting improvement in the braking.

Asked by for the 2003 Cadillac DeVille
Uneven/over-torqueing of lug nuts will also cause warping. Replace with new ones as suggested and use a torque wrench to tighten the lug nuts. Clean new rotors with soap and water rinse good and wipe dry with lint-free cloth or compressed air - better than using brake-cleaner for new rotors and pads.
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If they have been turned twice, then they are to thin & need to be replaced. The thinner they get the quicker they warp.