Wordpress running out of Apache memory on a Plesk server

I have a Wordpress 3.5.1 site that is located on my server. VPS - Parallels Plesk Panel 11.0.9, PHP 5.3.3, phpmyadmin 3.5.8.1 It is eating up Apache memory - running over 50% all the time and then shutting the server down when it gets so high. If I restart apache or suspend the domain and then re-activate it... it releases the memory and is good for about an hour or more before I have to do it again to get it to release the memory. The site is [login to view URL] It started doing this on Thursday 5/23/2013 of last week for apparently no reason at all. I have deactivated ALL the plugins and it made no difference at all - so I reactivated them.. ALSO - I have checked it for malware and trojan's and it is CLEAN. PLUS it has ran perfectly on the server it is on all year and ONLY started this high memory loss just last Thursday. I have also checked all the files and they are all correct and original. Don't know what is going on but I need this fixed ASAP. Thanks