I have an Epson Stylus 415 something-or-other and have always had some minor color correction issues, especially when the ink cartridges were low or old. But never to the extent that you all seem to be having.
Are you sure you have the right/best color cartridges for that printer and the paper set to the type that is recommended for printing with food coloring? I use the Kopykake chart to determine what color cartridges to buy - and have generally had decent color success. Not perfect, but pretty good with minor adjustments in Photoshop. http://www.kopykake.com/docume...PrinterInks-Xref.pdf
My bigger problems with this printer relate to the paper continually jamming . . .
Jaci (Ali's Sweet Tooth) probably has much better tips, since she seems to have had success with this particular Canon printer.