New pads in old calipers is bad news. Replace or rebuild the calipers and look at the brake hoses. When you push the piston back into the caliper, it squeezes all the gunk that has built up behind the piston, as the pads wear, into a confined place and tends to bind up the caliper piston.

Sometimes you can get away with pushing the caliper piston back in one time, but sometimes that doesn't even work. A second time nearly always ends with stuck pistons. I wouldn't be surprised if you will need new caliper pistons and new hardware kits as well as the rebuild kit. Rebuilt calipers are usually pretty cheap and come with those things included. If your 99 still has original front brake hoses, I think I would replace them, now, as well. You will have to bleed the brakes anyway. Gene