Hi, I have been working on my N/A FC which I bought about a month ago. The body has about 121,000miles and the engine only 3,000. A lot of work was done when the engine was rebuilt by a local shop, however there are still obviously issues I've had to fix as it is a very old car (although the new engine has had no issues whatsoever). I've already replaced a few sensors, replaced a missing wheel Stud, bled the coolant, and purchased a rebuilt power steering rack to install(mine is leaking rn so I just disconnected the pump). I'm going to check on the bushings at some point and replace them if the shop that did the engine didn't. The engines pretty much brand new so I don't really have to worry about replacing belts or coolant flushes at all right now, all that stuff looked mint. What are some things that I should check over for wear and/or replace in such an old car?

 

The electrical systems in these older Mazdas are quite awful. I would inspect all the grounds and battery connections. Verify all your lights gauges horn etc work well.
I'd also grease the window tracks, sunroof track.

 

Any rubber part has a finite lifetime. The expected lifespan of rubber bushings is about 15 years max. If they are exposed to heat and/or chemicals, than the lifespan will be shorter.
Check and/or replace all rubber suspension bushings such as the front suspension (control arm) bushings.
Check and/or replace all rubber mounts such as the motor, transmission and differential mounts. The RHS motor mount usually has a short lifespan because it's next to the exhaust manifold.
Check and/or replace all rubber boots such as the half shaft boots.
Check and/or replace all suspension components such as the inner/outer tie rods and ball joints.
Check and/or replace all shocks/struts including the front strut mounts.
Check and/or replace your shift lever bushings.