in your documents/my games/civ 5/logs folder. If you don't have logging enabled, enable it (google search can help you out with that), load your modded game again, then post your logs.
G
I actually just spent a few hours going through it - oddly enough, the only mods that crashed my game were additional civs - kinda odd. About 5 of them triggered crashes. Only one of them I liked (The Song). oh well no big loss.