Bootstrap intermittently fails

I wrote a little script that tries to simultaneously bootstrap 10+ EC2
instances. I get about a 50% failure rate with the error:

Bootstrapping Chef on ec2-184-73-xxx-xx.compute-1.amazonaws.com
ERROR: Network Error: Connection refused - connect(2)
Check your knife configuration and network settings

I suspect the Chef web server can’t handle that many concurrent requests?

Any ideas? Thanks for the help.