IE/Chrome unable to open PDF version 1.6 file via F5 LTM with SSL terminated on the F5

This could possibly be a chunking or compression issue. The only real way to find the problem would be a deep dive packet analysis. But, just for a shot in the dark try editing you HTTP profile and change response chunking to preserve. Another diagnostic attempt you could also ensure your web server isn't compressing the pdf(this will slow down transfer speed).