I have an 2001 ex, when the car has sat for about 6 or more hours the front brake make a loud thump and does not seem to grab tight, however the thumping stops after about 6-10 brake pumps and grabs tightly. I bled the lines last week, hoping that would be the solution, but it's not. Is my caliper bad? Any ideas?

 

It's possible that your caliper needs new seals (aka. a rebuild). Best bet would be to take it off, and thoroughly inspect it.