2000 Mercury Marquis Front wheel issues

I recently noticed that my front wheels lean in on the top off and on. I will be parked and it will be fine, both wheels will be straight up and down, then i will drive it, park it, and notice that one or both are leaning in on the top only, passenger side seems to be a bit worse about that. I'm worried it's going to be an expensive fix. I've looked into it being the camber and caster adjuster, a friend told me it could be the coil springs. I had to replace the driver's side lower ball joint a few months ago, and both outer tie rod ends so far.