I think you can do large scale batch processing work in CoolEdit, and it can do equalization like you say.

Not sure you'd be *happy* with the results; I'd do some test myself on a single file first. If a simple brick wall filter at 3k solved sound-quality problems on low bitrate MP3s, you'd think they'd just build that into the encoder.

(Actually, they do build that into some encoders come to think of it, but it's at a much higher frequency.)