What you're feeling is probably brake related... A worn lower ball joint won't do that. The lower ball joint in a McPherson strut setup is always going to be loaded because it supports all the sprung weight. Jack that corner of the vehicle up with your spare tire jack, enough for the tire to be fully off the ground, then grab your LCA (lower control arm) and shake up and down, feel for play. LCA's should have none, or undetectable amounts of play (the really proper way is to check play with a dial indicator). Either way, tolerable play for a LCA is in the thou's of an inch.