Extremely High CPU Usage

I converted my site from B2Evolution to 2.9.2 about a week ago. We have been experiencing REALLY high CPU usage usually 80-100% on a dedicated server I own. I was running out of memory but limiting apache to 32 connections stopped it. Something is really wrong and I have no idea what to do to fix it. I installed WP Optimize and WP Super Cache it helped a little but not much.

I get traffic but not enough to cause this, I normally get about 20,000 hits a day. I customized a Elegeant Simplistic template. So that could possibly be part of the issue as well.

Here’s the plugins I have installed…
Simple Press Forum
Contact Form 7
Exec PHP
Register Plus
Side Bar Login
Webby Chat
WP Super Cache
WP Optimize

Here’s the server stats…
Core 2 Duo w/4gb ram
Running Apache on Linux
Centos 5.4 64 bit

TOP
27448 apache 15 0 405m 124m 18m S 75.6 3.3 0:09.11 httpd
27444 apache 16 0 401m 120m 18m R 0.7 3.2 0:05.60 httpd
27368 apache 15 0 402m 123m 19m S 0.3 3.2 0:21.85 httpd
27374 apache 15 0 401m 126m 23m S 0.3 3.3 0:27.89 httpd
27449 apache 15 0 401m 125m 23m S 0.3 3.3 0:05.78 httpd
27509 apache 15 0 401m 118m 15m S 0.3 3.1 0:09.45 httpd

Also here’s the Mysql tuner script results….
Joins performed without indexes: 838
[!!] Temporary tables created on disk: 48% (1M on disk / 3M total)
[OK] Thread cache hit rate: 94% (2K created / 46K connections)
[!!] Table cache hit rate: 14% (533 open / 3K opened)
[OK] Open file limit used: 30% (793/2K)
[OK] Table locks acquired immediately: 99% (6M immediate / 6M locks)
[!!] Connections aborted: 15%

——– Recommendations —————————————————–
General recommendations:
Adjust your join queries to always utilize indexes
When making adjustments, make tmp_table_size/max_heap_table_size equal
Reduce your SELECT DISTINCT queries without LIMIT clauses
Increase table_cache gradually to avoid file descriptor limits
Your applications are not closing MySQL connections properly
Variables to adjust:
join_buffer_size (> 768.0K, or always use indexes with joins)
tmp_table_size (> 192M)
max_heap_table_size (> 192M)
table_cache (> 1024)

My site is http://www.swaggrabber.com. I would GREATLY appreciate someone giving me some ideas of where to start. We are stumped and have tried everything we can think of!