I don't know the answer to this question, but I can attest to your situation. My '00 brake pedal also squeaks as I press it / release it. It almost has a pneumatic sound to it too, as if I am stepping on a cat lung or something. I haven't really had a chance to diagnose it yet, but I'd be interested to hear of your findings. All I can say is that it went away and now it's back since I degreased my engine compartment. So I thought it was an interior grease point issue, but now I'm a little concerned.

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'00 Rodeo LS 4x4; "K&N" cone filter; S/S Manik Front, Rear, & Nerf; 'Modest' sound system; 1.5" R'ooper lift, 265/70/16 Dunlop RVxt, Skyjacker Hydros, OEM LSD (sans G80 code)