You might run 'show processlist' in mysql and take a look and see what's going on. If you don't have privileges to kill processes, or can't figure out who or what is hogging the connections, you're probably up a creek; complain to your host or system administrator. If you are the sysadmin, you must have a very busy site --- I'd consider a seperate server to run queries....
And maybe cutting down on using mysql_pconnect when a mysql_connect would work instead ...
My $.02,
