Hey guys I noticed my truck misfiring and popped the hood, got a crack in my distributor cap, what would cause this to happen? Thanks

 

Old age. They don't last forever.

 

Thanks, and I just pulled it off and the some of the contact points are soo ground down the rotor started digging into the plastic around it and there's a part of the rotor arm (I guess that's what it could be called) is bent

 

Yes a crack can do it.