I rooted my phone after a few days of owning it in mid January. Went crazy with app linking, tweaking the kernel's governor and max and min speeds, blocking OTA, and a few other tweaks. After about a month, I experienced similar overheating issues. I lived with it for a while.
To some degree, I think the overheating contributed to the screen flickering problems. Decided to redo my phone last Sunday by flashing the 5.1.1 image. (I haven't upgraded to MM.) Rerooted it, reinstated app linking and OTA block, but I no longer tweak the kernel or do anymore additional things (aside from using Titanium Backup, which is great as there's no custom recovery for Sprint based stylos). I've also cut back on the amount of apps I use. Initially, I used a web wrapper app for facebook, twitter, and a few other social media sites. Now I have the fb, twitter, fb messenger, and Instagram apps back on, but all other social media is accessed via the stock browser. (Personally I don't see much use for snapchat, etc as Instagram has similar features already as far as I can see... I can only keep up with so much anymore!)
As far as the screen I fixed that problem by carefully disassembling the phone, and then disconnecting the digitizer. Then I sprayed some compressed air to clean the digitizer jack and cable. Afterwards, reinserted the digitizer cable, and reassembled the phone. Now it works great! Haven't had any overheating or screen flickering since last Tuesday! I still have some cash ready to buy a backup/replacement phone, but I might be able to put that somewhere else soon.
Scroll to the last post here to see how to disassemble the digitizer, and more on the screen flickering issues in the thread. The video also has instructions for replacing the screen/digitizer yourself, if needed.
http://androidforums.com/threads/screen-flickering.1022019/