One helpful tactic I've read to find problem custom content is the 50% method. If your game runs fine without any CC, divide your CC in half and add half back. If it still works fine, you know the problem item or items is not in the half. If the game does have a problem, split that half again until you find the problem item(s).
I can't claim credit for that strategy, but something I've always done when using CC is to add one piece at a time. Then I load and play the game for however long I'd intended to play, which will hopefully flush out a problem if there's going to be one. If all's well, I add another piece next time. Then you know right away what item may have caused trouble.