[Shotimes] power brake noise

[Kevin & Cheryl Airth]

My 93 ATX has 135K miles and a soft brake pedal. I have replaced all four
calipers, the master cylinder and all four rubber lines along with a complete
fluid change and multiple bleedings. No change and lately I can hear a sound
like a piece of metal is flexed back and forth when the brake pedal travels a
certain distance. A clicking or popping sound. Can the brake booster make the
noise? Maybe traveling too far?
Thanks.
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