This started a couple of weeks back. It started with 3 codes, a misfire, bad coil and stuck rich. I have since done a tune up replacing all the spark plugs, the bad coil and even the O2 sensor. It is now at a point where the CEL is not on but it still throws the P2196 with a brand new o2 sensor just installed. I am stumped as what I should be checking for next. It seems to run ok but idle is not as smooth as pre-codes.

The truck is a 2006 XLT. Any suggestions or help is greatly appreciated.

 

You may have a leaky injector (or more). This can cause a rich condition, something the O2 was picking up and reporting the code.

There's a recall I believe on Ford injectors, so this may not cost you if they end up being the problem.

 

For the 2006 Models? I did notice that one spark plug was really black.

 

I would replace the injector on the cylinder with the black plug. Do it soon before you ruin the cats.