Power-steering, transmission, and differential fluid. Mine were all black at 75k. Maybe clean the boost solenoids? Definitely check for any sings of gasket leaks. Other than that? Don't make problems where there are none. You should've installed a DV+ while you had the water pump out
If you haven't done it yet, upgrade your transmission mounts. It take 5 minutes to do and will make a world of difference in shifting. I was getting locked out of gears during hard pulls and while turning. Now I can shift at redline again without a hitch. Go with UUC. The m3 mounts are just as soft as stock. I actually filled my stock mounts with Liquid Nail polyurethane (6.99). The result is a solid bushing about the same durometer as the solid UUC mounts. Just requires a day or two to let them "cure."