I bought a 93 325i late last year, and I didn't have much money to spend (none really), so I was limited in what I could afford. My supension is also clunky in the rear. This is most likely the rear upper shock mount. It's about a $50 part. I need to just replace the whole suspension but again, $$$ is the issue. I know that bimmers are expensive to maintain, but I had to have a nice car. Even though mine is a bit of a basket case, and I raced it (autocross), so now it's even worse, I still love it.
Mine is also a bit sluggish on the acceleration, more so lately. I am about to order a K&N airfilter ($40-50) and I hope that will help. My current filter is pretty gross, and it's my bad for not replacing it long ago. I also warped my rotors racing. They were brand new too. Darn it!
I think you will like the 325 no matter the issues. I love the recaro (based, or real?) leather seats, very much like the recaros in my VW GTI that I previously had. The interior ergonomics are excellent. Everything is laid out intelligently and accessible. Even down to the dead pedal being in the ideal place. I drive my mom's S4 (also '93), and though her car has a higher trim level, I prefer mine on driving comfort alone.
I know if I could dump a few grand into her, she would be a top notch ride. Hopefully I can do just that someday soon. I'll be sticking with BMW until I can afford my Porsche.
-Joe