2001 Chrysler PT Cruiser pulls to left then to right

Hello just bought my first pt and when I test drove it it was pulling to the left abit they did a front end allign and found bad ball joint and tirod they replaced it then it started to pull to the right they checked the specs on allign and rotated tires then replace 2 of them well it didnt seem to be any better the then replaced the rotors on front and re ground the drums on back balanced all the tires etc. It is still pulling when I apply the breaks intermittenly to the right. Is it possible I have a calaper problem or what thankyou in advance. First time buyer