Need help for installing jelly bean based rom after installing kit-kat based rom topic

Hello everyone,
Now I am using Nexus 5 Experience - CM11 Based rom but Whenever I install Jelly Bean based rom's like CM-10.2.1 MIUI etc, Phone take too long time to boot and WiFi doesn't work,
What I need to do to install previous version of android?
(Sorry for bad English)