I don't use the code Amazon gives, I wrote my own. But, Amazon usually keeps their ads in iframes. The reason I'm using iframes now, which wasn't how I use to do it, is so that the forum software isn't bogged down by reading 1000s lines of code. So, I keep the code for the random feature block, still on the server(mitch.chemicalforums.com), but not on the forum. If you need the code let me know.
I don't know what UTF-8 is, but if you recognize the formatting, it must be the way Amazon encodes their affiliate links.