I already did the Still In The Dark quest, and I dressed as a Khan in Vault 3, just to make it easier. I wanted to help the Khans later, so I didn't want to kill Motor Runner. I sold him some jet and psycho as he initiated dialogue. Took the pulse cleaner, and I was on my way. Well several hours later in game play, Diane wants me to deliver a drug package to Motor Runner. Who doesn't initiate dialogue anymore, can't even talk to the guy. So I don't get to complete the quest, hurray! I guess you have to do both quests at the same time, if you don't want to shed any violence in the Vault.

Anyways, its been a very, very long time since I came across a quest breaking glitch like this. I feel used lol