At this point we've contacted Craigslist several times, including Craig himself. Craig forwarded to another person there, but we have not gotten a single response from who he forwarded to. We've also dialed back our fetching of Craigslist feeds drastically, and make no more than 3-5 requests per minute per server. No CL feed is fetched more frequently than once every 4 hours.
You're getting a trickle of posts because their automated system lets servers out of the penalty box for a while before they hit the the limit again and get put back in the box. So for a few hours a day a portion of our servers have access to fetch the feeds.
That's the status as of now. We'll keep bothering them about it and hopefully will get a response. We can also try dialing the fetching interval down even further to see if we can get under whatever the limit is.