I have been using inks from inkjetmall.com for a number of years on my 2 3880's and have no complaints. Their blacks are deeper than Epson's too.The inks are great and work with the same profiles as Epson inks and cost a lot less. I have had virtually no clogged heads, maybe a few missing bars from time to time. More important, with regards to this question, they are very knowledgeable with Epson printers and can often put one in the right direction. They also have a very good "community" page.
Even if you do not wish to purchase their inks it is worth looking in on them.
Good luck
Martin