Use TESV edit, google it and you will find it, extract the ZIP, click it, And it will run a test on your mods.(editing is optional, It can also be used for this purpose), It will run and stop and show an error message when something goes wrong, And tell you the mod that caused it. Loot/BOSS aren't perfect, if you get crashes even after they sort your load order, TESV edit will tell you the mod that conflicted.