Correct I am starting to wonder if i have an electrical short some where? Truck started and ran like crap this am then I was sitting at a light and it seemed to be better. Problem is i could throw a 1,000 dollars of parts at it and be in the same place. Mechanic will just throw parts at it. Orginally I was getting PO171 , 172 I replace back O2 senosr drivers side and now its throwing a PO138. I hate all this computer ****.

 

Northern Goat I didn't read your OP. How many miles? plugs, wires, clean throttle body. When was the last time you ran injector cleaner? Start with the simple first. Lets us know how it goes.

 

Well atleast we know that your post cat o2 is running rich.
You never answered if you changed with them OEM sensor or another.