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I use Acrobat Pro although I'm aware that costs money... specifically, what kind of editing do you want to do?
 
Illustrator can make edits to your pdf one page at a time. Other than that you should get the native document make the changes there and make a new pdf.
 
PitStop Rules!

If you have the coin, using Enfocus PitStop Pro is the best way to do a myriad of edits on PDFs, both single- and multi-page.

You can edit not only text, but do a heckuva job preflighting, editing, trapping and the like from a prepress perspective. Want to change color mode of an image? This will do it..

It's a plug-in for Acrobat, so you'll need the full version, plus an extra $600 or so for the plug-in. Pricey, yes, but well worth it.
 
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