I have a 98 Isuzu Rodeo (I know, wrong group, but I can't find a good
Isuzu one. Besides Isuzu made the Passports, so surely I'm close
enough).

Whenever the engine is running and the clutch is out, a repeating
squeak can be heard as if a belt is slightly loose or needs lubing.
Pressing the cluch causes it to go away even if just idling in neutral.
I sprayed the serpentine belt with some lube, but it didn't make a
difference.

Any ideas as to what I can do to fix it?