Again thank you for being so fastWell, those are the most recent Spark EZRoms so they're the right ones.
Try making a backup of boot, system, data within the TWRP backup section then and copy the android folder from sdcard0 to your computer. You may want to copy anything else in sdcard0 that looks like it's needed. Make sure you store the backup on /sdcard in TWRP, not /emmc!
Once this is done use Phoenixsuit to flash your present EZRom again. Try using update first, to see if it fixes the problem. If that doesn't do it then try flashing without formatting. If it won't boot to Android then restore boot, system and data in TWRP then copy the files/folders from your computer back to /sdcard. Make sure you copy these files before you boot into Android or you'll loose some big apps and app settings.
What I think may be happening, is you have some failing sectors in your flash memory in the boot or MRB area. That would explain why it fails later and seams to be getting worse. But that's just a guess!
I did have problems with CM11 and Omni where it got slower and slower so I just used CM 10.2 but I think my newer 4.2.2 is more stable. That's why I recommend you try it. And if you still have the same problem I'd say it's a hardware issue, flash memory being the most likely cause.
There is one very risky option. Use the terminal in TWRP to over write just the MRB using dd. I could send you the MRB file but there doesn't seam to be raw block /dev device for all the flash memory dd would need to write to. So it's probably not possible.
You did ask about bookmarks. If you're using Chrome then it in /data/data/com.android.chrome/app_chrome/Default.
I will try and implement those suggestions asap. However as you mention something about bookmarks. Unfortunately I needed to use the browser that came with cm11 to store those bookmarks. So they are trapped there. Is there any location I could look to extract those? After that, I could try all the above suggestions in case they work but still not have any severe data loss in case they don't.