Help, Weird rapid clunk and thunp felt in brake pedal

[dchfm123]

2011 Silverado 1500 4wd.  This morning I felt and heard a clunk while my truck was deaccelerating, I think it happened when down shifting.  Later today I randomly heard it again several times.  Then on my way home it started doing it rapidly, it is a clunk/thump sound and I can feel it in the brake pedal.  It slams the pedal back into my foot rapidly.  I was at first thinking it may be a drive train issue but due to the slamming back on my foot leads me to think that it is brake related.  It happens mostly when coasting or braking but accelerating too.  Any Ideas?

[dchfm123]

Oh and thank you for any help or ideas offered.

[dchfm123]

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[newdude]

Pull those front wheels off and check your brakes.  Sounds like some really worn/warped pads and rotors, or pads cocked in the caliper bracket or a caliper issue.  Might want to check the rear as well just in case, but typically if you feel it in the pedal strong, its from the front (shortest braking lines from the ABS). 

[dchfm123]

I plan on doing that.  Its not a warped rotor, but might be a pad or caliper issue.  I pulled to abs fuse to rule out possible abs issues, and that did not make a difference.  Time to pull the wheels.