High load factor with Apache 2.2.6 and Solaris 10

I'm hoping someone out there can provide me with some solution to the
problem I am having. Here is the breakdown:

Our previous webserver was a Sun 420R running Solaris 9 and Apache
1.3.37. The system ran fine but would occassionally get overloaded
and show load factors in the 20's. We decided to replace this machine
with a Sun V480 (2 CPU, 4GB). This new machine is running Solaris 10
and Apache 2.2.6. This new machine has more horsepower than the old
420R so we expected to see improved performance. The machine is
serving up the exact same webpages from our NAS device that the 420R
was serving up. However, the new server is randomly showing load
factors as high as 60 and intermittently running httpd processes that
grow up to 1GB in size. I've set the KeepAliveRequests to 500,
KeepAliveTimeout to 3 and MaxRequestsPerChild to various values but
continue to see this behavior.

Does anyone know why Apache would be doing this? Suggestions to fix
it?

Help!