Hi there...bought a used 2000 626 from used car dealer 3 weeks ago, said he just got it inspected. Four days later, CEL came on; they replaced one O2 sensor. The next week, CEL came back on, replaced EGR valve. This week, CEL back on again. They want me to bring it back in. How many more things can it be?

Also, a clunking noise that sounds like it's coming from passenger back wheel only when going over bumps at low speed...CV joint?

Tonight when I took it out to try to pinpoint where the noise was coming from, when I pulled in my garage and turned the car off, I heard a loud clicking noise from under the car that continued for about 5 minutes. Any suggestions? Thanks so much!