turbguy, from the pictures you have posted, I see two things. First I see colors that fade in and out and I believe this is cause by ink starvation of one or more colors. What I am saying is there may be sufficient ink to print a perfectly fine nozzle pattern of a given color because that does not use very much ink. However, when you try and print a much larger area that requires sustained ink flow of several colors so they can blend and product the correct color, one of them can not sustain the demand from the printhead and as it fades the color goes from correct to some off color. Ink carts that have been refilled several times or let sit for long periods of time, or just begin to dry up can cause this. Of course, clogging can do the same thing.
A much better test for you is not the photo you used, but a professional color chart or a set of 6 color bars which are the pure colors of Black, Cyan, Magenta, Photo Cyan, Photo Magenta, and Yellow. Print half a page of such a pattern and upload it hear. This helps to prove two things at once. A. Your ink carts can supply pure ink over a large area and won't fade. B. Your printhead has no bad nozzles.
The second thing I noticed from you picture is that you have all kinds of streaks. This is not banding,... it is streaks. Streaks are ink jet nozzles that are not firing or creating ink drops. You should be able to look very close at your nozzle test pattern and see some of these misisng lines. They are there or you would not be getting streaks. REmember the streak may not be white in a photo since all colors are made up of the 3 primary colors. To get a streak, all you need is just one of them not firing on that line. The question is, is it because of a clog, or a burned out nozzle, or a bad electrical connection, or a bad timing code strip.
So, to help us and yourself, get a set of color test bars off the internet, print them and print your nozzle check pattern and post the results.
Then we can help in more detail. One other point, a bad purge unit can also cause similar problems. If it is clogged, it can't successfully Prime the printhead with sufficient ink. IF the ink is not sucked out of the ink cart then sufficient flow from the ink cart is not started and ink may flow in spurts. Think of it like a garden hose. Sometimes when you turn it on it takes awhile for all the air to get out of the hose until it get full of water. It gets fixed very fast because of the water presssure, but ink carts don't have any back pressure. This totally depends on an end to end vacuum being created such that when one picoliter of ink is pushed out of the nozzle the same picoliter will flow out of the ink cart into the head. It has to be an unbroken chain or all it does is suck air. Try to syphem gas out of a car by just sucking on a tube, it won't work if you get one air bubble in the path. Looking forward to your new images.