I'm aware of that addict I was just showing why I was confused as there was no connector on the wiring harness but there was a terminal connection if you look at the second pic. Thanks though some people may not know and hopefully those pics help.

 

oh haha im sorry, i must have read that too fast.

 

Your O2 will not show any codes when it is going out. They tend to start getting slow to respond when they are about to die, leading to false readings that normally cause rich running. There is a test in the FSM to check proper function. It's a $50.00 part off eBay for the correct direct fit Denso.

 

I just pulled the plug off of my truck to compare it to your plug. Mine is the same as yours. I dont think that is your issue