One major problem with all the above advice. The color dyes are stabilized from fading with a formaldehyde solution, somewhere in the development process. If you just wash the slides in water (which is how I would start), the dyes will rapidly fade over time.(posted 8610 days ago)You need to re stabilize them. The Kodak process took the formaldehyde out of the final rinse years ago, the final rinse is similar to PhotoFlo with an activator for previously introduced less hazardous formaldehyde compounds early in the process. The other processes (Jobo/Tetnal, Beseler, Unicolor, etc) still have a formaldehyde based final rinse/stabilizer step. Some of thoese sell that step separately from the whole kit. You should use this as the final step in recovering the slides.
And of course, start by removing them from the mounts. While they are wet, watch that they don't stick together.
Overall, I would remove them from the mounts, wash them in distilled water, with several changes of water, then stabilize them, then remount when dry. If you wash with water, you really don't need an acetic acid step, but if you want to do that, it probably wouldn't hurt. I would use 1/2 strength stop bath, and NOT indicator stop (could add the indicator color to the slides).