Checking your registry one by one is probably not the best idea, I understand your pain though, browser hijackers are a pain. I will assume that you already tried the following:
Checked your browser add-ons for any unrecognized extensions
Checked your programs for any unrecognized or suspicious activity
Installed RKill to kill any malicious processes
Ran a full scan with antivirus software
Scanned your PC with Malwarebytes, Hitman Pro, ADWCleaner, Zemana.
Used a third party application to attempt to clean your registries (Or in your case, did manually, I would still recommend trying a third party application)
Reset your browsers to default settings
Used browser specific clean up tools (Each browser has specific cleaner, like Chrome clean up tool)
Did all of the following steps in Windows "Safe mode with networking"
There are also adware/browser hijacker removal tools, like Bitdefender's adware removal tool. Nortons removal tool.
If yes, I am afraid, all of the conventional methods are exhausted at this point. And I too would like to know other possible solutions to this situations, if these do not help.