Yes 1.3x are pretty much a big joke.
I would update to the latest firmware, it's the most stable out of all the 1.3x. There are a few fixes, and most of them can be found by looking through the forums, if you have problems still after the latest update. Like disabling a bunch of features on the router helps the stability a bit. But in the end 1.3x is pure ****tastic, so I don't recommend you suffer through the pain of it all, to find the root of the problems. I would suggest you just look for a different router, cause this issues isn't going away for a while.
I'm happy that I don't have to deal with 1.3x cause my problems went away when I got a netgear dualband with dd-wrt. No matter what I did to 1.32 firmware of my dir 655, it just couldn't function well for a very day router. I'm sorry that you fell into the 1.3x entanglement, I feel your pain as I too have loved this router in it's prime when i first got it, but sometimes you have to cut your losses and look else where......