persistent MySQL connections

in advande sorry for the bad english, i got a big spike in visits yesterda and my website went down, i tought that my server was unable to handle the spike or someting and ask to support (dreamhost) and got this aswer:

“Sorry to hear that you’re having trouble here! Unfortunately, the problem
that caused your site to stop working wouldn’t have been helped by
caching. It looks like you might have a plugin installed that’s opening
persistent MySQL connections to perform its queries. What that means is
whenever a page was loaded that used whichever plugin was causing this a
MySQL connection was opened to your MySQL server and then never closed.
These built up until your MySQL user got locked out due to having too
many open connections (300). It’s hard to say which plugin is doing this,
so you’ll likely need to do some troubleshooting on your own. If you’re
unsure where to start, generally disabling all plugins but your most
essential ones is a good place to start. From there, you might try asking
for some help in the WordPress forums here:

Support Forums

Listing the plugins you’re using and asking for help figuring out which
ones might be opening persistent connections might be a good place to
start there. Alternately, you could try searching that forum for each
plugin you’re using to see if there are known issues.”

i had search the forums and only found one similar post whit karma coments as the causing problems plugin, but i dont use that plugin, this is the list of the ones i have on:
Akismet, all in One SEO Pack, Contact Form 7, Exclude Pages from Navigation, FD Feedburner Plugin, Featured Content Gallery, flickrRSS, Get Recent Comments, Google XML Sitemaps, Hybrid Hook, Ozh’ Better Feed, Permalink Redirect, SEO Smart Links, Smart Ads, Subscribe To Comments, Viper’s Video Quicktags, WordPress Database Backup, WordPress Thread Comment, WP-Polls, WP125, WP Super Cache, Yet Another Related Posts Plugin.

How could i find the plugin that is causing me problems? or any other idea to troubleshot this?

thank you in advance