why is my automatically installing apps while turn on data?

[AC Question]

Many apps gets installled automatically when connected to Wifi internet such as Apus, Batary Doctor, 360 security Light, Myntra, flipkart, phone booster.....and many more. These faltu and disgusting Apps gets installed automatically and eats up lot of space on phone memory or RAM.

I use to uninstall then now and then when got installed. And unchecked the option to deny installation from unknown sources from "Settings>>Security>>Device Administration".

Now I am not getting those apps installed but APUS (a unwanted and disgusting app) starts installing itself but due to above option it couldnt continue its installation. BUT during this process and when my cell is connected to wifi internet, it hangs my cell and I could not even go to Home screen and if opened cant come back on display screen.
However it gets faster if I disconnect from wifi internet.

As a solution somewhere in forum I have formatted my SD card, then restore my factory settings, restart my cell two times a day.....but still the issue remains.

could you please help me to resolve the issue?

 

[belodion]

Would you feel competent to reflash the stock ROM via a PC? Sometimes that is the only way to fix it.

 

[B. Diddy]

Welcome to Android Central! Try doing another factory reset, and this time after finishing the Setup Wizard, go immediately to the Play Store and prevent any apps from automatically reinstalling. Now see if those problem apps still automatically download and install. If they do, then belodion is probably right--you have malware installed somewhere on the root that is doing this, which requires the firmware to be reinstalled in order to get rid of ti.