unusual high server load- how to trace down the faulty scripts?

Hello people,
first of all I am sorry if this is a stupid question, but:
I have a dedicated server running CentOS, with a quite powerful hardware: dual 3 Ghz processor, 2 Gb Ram, and I`m running about 25-30 sites.
from a while the server has unusual high loads, and I keep getting mails from WHM that "the CPU has been maxed out in the past 6 hours".
we also had hacker attacks on the server, but it`s cleaned up.
my question is:
how can I trace down what processes are running on the server, because all I can see that mysql and httpd are causing the high loads, and in this case:
how can I trace down if there are any php scripts causing the high loads, maybe incorrect scripts, etc.
is there any tool for this?
thanks!

If httpd and mysqld are causing high loads, you can try setting them to a lower log level. Look for the same thing being done over and over. Also, if you're using perl or python on the sites, you want to run those in a debug mode also.

Hi likwid,
thanks for your reaction.
I had perl running on the server, but I changed it`s ownership to root, and made it accessible only for root.
this cutted down the usage of perl.
the sites on the server don`t use it anyway, so this was useless.
python is not causing high load, so this one is ok.
the problem is mysql and httpd.
how do I set them to a lower log level? and where do I find all their logs?
thanks