We had similar issues (flickering and continous moving of the screen horizontally) for 2 of our dell latitude 3460 running on Debian 9.3 configured with i915 driver. Observed that it was mostly on terminal with some key combinations like CTRL + C but happened randomly.
We choose advance option to boot in with old kernel 4.9.0.3 and issue seems resolved. Likely problem with kernel 4.9.0.4 Let us know if you need more info in order to fix issue. Regards, Aslam Sayyed
