If you think the filament has collected moisture, you may be able to mitigate that by dehydrating it in a source of heat. I purchased a simple food dehydrator and chopped away the internal food trays to accommodate a spool. The maximum temperature for the dehydrator is just about right to force out the water over a day.

I hadn't considered it before but if you're getting water in the nozzle, it may indeed affect the feed rate.