There are three possibilities that come to mind, since I've had many and various issues with the 9900 over the past two and a half years. I'm now working on my third and last warranty extension, good insurance. If you've had any recent paper jams there could very well be some debris stuck to the print head that could cause this sort of problem. If you do a lot of borderless printing you might want to check the pads that collect the ink overspray. Due to the fact that these pads are somewhat damp they do tend to collect various fibers that can be picked up by the print head and then cause the problem you have indicated. Also, if you do a lot of printing on canvas or cotton rag materials, make sure you use a good vacuum to clean the paper feed area on a regular basis. Again, a lot of debris could be collecting from these materials, especially if you are allowing the printer's cutter to trim the product.
As far as the cleaning regimen is concerned, it's not usually a good idea to do that many cleanings consecutively, especially the high powered cleanings. Epson warns against this as well. If you are seeing this sort of problem or any clogging issue you should probably do no more than 4 or 5 cleaning cycles and then let the printer sit idle for a few hours, or overnight if possible, before another cycle is run. In this case however, it may require a physical cleaning of the print head or at worst a replacement. Also, the aforementioned 'soaking' of the print head may be of some help. Of course another area of concern could be the Wiper Blade. There's another thread on the forum that shows how to easily access the Wiper and check for damage and replacement. This should be an easy fix according to this thread - Epson 7900 from the inside - out New « 1 2 ... 38 39 ». It's a long thread but you'll find the info at around midway I believe. Follow from the beginning and you will find the procedure and other very useful information.
I hope this helps.