After giving this some thought last night, this solution *may* do what you're looking for but it seems a bit convoluted to me.

Adobe offers a PDF to HTML conversion utility here. I've used this to convert a PDF to HTML so that I could parse out the info I needed for an app I was working on.

If you've just got straight text in the PDF, theoretically you could do the conversion, do a HTML to text conversion, make your changes, then write the whole mess back to a PDF using the PDF modules.

Like I said, that seems like a long way around to the solution, but it may work for you.

Update: I seem to remember, that depending on your version of Acrobat that you can edit PDF files if you've got the originals? I believe it was Version 5. Version 6 may do that too, I don't know.

There is no emoticon for what I'm feeling now.