Mine does the inconsistent popping thing when I am braking, and it turns out my ball joints are shot. I got under the truck and put it on jack stands and put a pipe under the tire and lifted up on it with my toes (wife was not home!) while taking a good look at the ball joints themselves. That's the only way I saw that they were bad. Just lifting on the tire didn't seem loose, but there was clearly movement at the joint. I have my parts on order and hope to have it done by a Ford dealer mech as a side job for $200 bucks labor. At that price it's not worth the drive to lowe's to make the seal driver.
I'll let you know if it cures my woes.
Scott