Annoying bumpsteer, braking, steering issues

Ever since I bought my Stang it pulls to the left under light/moderate braking. If I brake harder it doesn't pull as much. The rotors and pads are nearly new and my mechanic said that the brakes themselves are fine, but the wheel alignment needs to be checked.
The alignment shop corrected the camber and toe (the camber was quite a bit off but the toe was OK) and things improved but the car still pulls to the left under braking (just not as much). As far as I can tell, the suspension is stock and the front springs are original. Another thing I've noticed is it has a fair degree of bumpsteer and I wonder if the two problems are related.
Finally, I've also noticed a creaking/clicking noise coming from the front (I think on the passenger side) when I turn the steering to the right but not when I turn it left. The car steers straight when the steering wheel is straight and there's no vibration through the steering at any speed.
Can anyone help with some ideas how to solve these issues? I don't want to pour money into a bumpsteer kit, camber/caster plates, or any other parts unless they're likely to help.

Thanks, a sticking front passenger side caliper does make sense but what about the bumpsteer and the creaking noise when I turn the steering to the right at low speeds? Balljoints? Tie rod ends?

Well, I thought I'd report back because I've managed to get all three issues solved in one hit. The problems were worn tie rod ends and worn steering rack bushings. I even discovered that a previous owner had, in fact, lowered the front & rear suspension by 1".
I had the inner and outer tie rod ends replaced on both sides, and new urethane steering rack bushings installed (not offset). Now the car stays dead straight even when I brake hard, the bumpsteer has gone, and no more creaking from the passenger side when I begin to steer right. I'm a happy camper.

I had already bought the Energy Suspension master bushing kit so I just used the steering rack bushings from that kit. I'm happy that all three problems are solved now and the car is so much more enjoyable to drive.