Can you be a bit more specific? How many items are in your feed? Would it be possible to get a look at your rss feed?
At a minimum, you can use an editor to update the missing fields.
I've written software that creates and manages both MRSS and JSON feed files. I'm in the process of updating the MRSS product. I'm looking to add an import from other RSS sources. Unfortunately, that won't help you now. Sorry I couldn't be more helpful.