Those sound like the hex values used for old Microsoft "Smart" quotes where it tries to helpfully replace correct ASCII punctuation with what winds up being unreadable on other platforms. There's ancient code from 2003 that should still work, or you can work out what the correct corresponding character would be and fix just the things you're seeing (e.g. s/\x91/`/g I'm guessing) and run some variation of perl -i.bak -pE 's/...//' input.txt over your file(s).

Edit: Just to be clear, it sounded like whatever you're viewing files with is displaying the non-ASCII character's hex values in angle brackets. If you've literally got four characters "< 9 2 >" then you'd want the above advice.