If there is no CTD for a new game, only loading a specific save, then you have proven that your installation, load order, and mods are not the cause of the CTD. That leaves two likely possibilities:
Applicable to LE only: You may have the widely known problem explained here. It explains how to work around it manually or use the provided SKSE plugin.
OR the save is corrupt (this is the most likely case)... If corrupt, the only solution is to start a new game, or use an earlier save where you know it's before the action you took that corrupted the save.
If you are wondering how the save became corrupt, it's almost always this... Golden Rule
Example of breaking the Golden Rule... Not starting a new game when adding Toys Framework for the first time (it's the requirement). When install instructions say start a new game, do I really need to start a new game?