That's strange. I rooted after installing official 4.3 OTA and never had any problem installing a custom ROM. Using Root explorer check in system/app if you have any Knox bits remaining. Maybe it can be the reason why ROMs aren't installing on your phone. Even I have the ML3 bootloader. Also when you're stuck on Samsung Logo after flashing ROM wait for 10 mins or so and then long press the poeer button which will lead you to the Recovery mode. There again wipe cache and dalvik and reboot and select no when prompted something about lost root.
Sent from my GT-N7100 using xda app-developers app
Lucky you! Just checke system/app no knox left. hmm ok I'll try AGAIN later :/ after flashing and stuck on samsung logo, should i turn of my phone? or just let it stuck and then press power button after 10 mins?