It sounds like you are describing banding or something similar.
Try  nozzle clean, and then check whether you saved that adjusted image in the wrong color space. If it has an embedded profile, Qimage will tell you. Look at the hotbar located at the bottom of the Qimage screen while you hover the mouse over the thumbnail. See if there are asterisks before and after the color space that shows there.
Please note what Qimage reports.

My bet is a nozzle clean.... sometimes those lines only show when there is a sky background or some other large expanse of one color.
If you want to, you are certainly welcome to email me the JPG that prints lines, and I can check it out here on my R 1800 as well as see the color space.
Fred

wathree.ssz@verizon.net