FM makes nice PDF graphic look bad. Why?

We are having a tough time with graphics that were created in Interleaf.  I make a PDF of the Interleaf document and it looks/prints excellent, just like the original in Interleaf.  But, when I import it into FM and print, it looks quite bad.  If I open the same PDF in Illustrator and save it as a PDF from there, then import into FM, it prints fine.  Same thing if I save the same PDF as an AI file and import to FM.  It prints fine.  Do I really need to resave all my PDFs in AI or is there a better way?  It seems like FM should be able to handle the original PDF as well as AI, but it doesn't.  Maybe I am missing something...

Any thoughts?  Thx!!