My '96 does the same thing, but usually on cool/cold mornings, or humid/rainy days/nights. And always after it sits overnight. After a few brake applications, the problem is gone for the rest of the day, until overnight, to the next day.
The issue is with the brake material. I've pulled my wheels and checked the brakes about 7 times this spring/summer, and there are no issues with leaking wheel cylinders, bad park brake cables, or hardware. Brake shoe thickness is good.
I can't remember what "grade" of brake shoes I got from the last brake job 4 years ago. So I am guessing the issue is with the brake material used. Like I said, the issue is gone, once I apply the brakes a couple times. Then it is fine. And, it isn't a daily issue. Only happens on the conditions above.
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