Step 1

Four Step Ultimate Troubleshooting Guide

Step 1. Disable all mods and test un-modded

What are we doing? We're going to run the game without any mods.

Why are we doing this? We want to rule out any hardware, PC software, or game file issues and ensure your game runs stably in vanilla mode - without any mods - no scripts, no addons, no trainers, no customizations at all. This assumes you didn't mod game files directly, that you used a mods folder.

You don't need to uninstall anything at this point.  

Instructions

Simply rename dinput8.dll which you will find in your root folder (where GTA5.exe is) to dinput8.bak and start your game. This is an easy way to disable all mods and can also be used to play GTA online. 

If your game nows runs properly without mods and without incident, move to the next step. You now know your game itself is fine. 

If it doesn't run, start with a Verify Integrity, and worst case a complete reinstall with a new saved game file as well. Remember not to mod your game directly, use a mods folder.

 Important: this process assumes you installed all GTA 5 modding essentials. 

Important: reinstalling a game more than once is a complete waste of time. 

 Step 2. Disable your scripts folder

Four Step Ultimate Troubleshooting Guide
Step 1. Disable all mods and test un-modded
Step 2. Disable your scripts folder
Step 3. Disable your mods folder
Step 4. Disable your asi and root mods