Front Cobra Caliper Question

I've had a clunk going on with my front Cobra brakes for a while. They clunk the first time I back up, then again when I go forward again, and occasionally clunk when I go over a sharp bump. When I first checked the calipers, I could wiggle them in the bracket a bit by hand. So I got a Raybestos caliper hardware kit and replaced the slide pin and anti-rattle clips. For a few days the clunk was gone, then it came back again. I can't move the calipers by hand anymore, but I can slide the pin back and forth with a tiny push of a finger. It doesn't slide freely, but it's only a small effort to get it to move.

Should the slide pin be so easy to move? I would have expected it to take a good bit of force to move the pin. I'm tempted to pay the extra $$$$ and buy a Motorcraft Cobra hardware kit (BRPK5610) and see if it helps.