Just go a new factoy y-pipe put on today under warranty and on the way home my CEL flashed on and off repeatedly for about 1 min then stayed off. What is that about? The truck is also idling rougher now. When I gave it to the dealer I had my meth turned on. It was off when I picked it up. They put 3 miles on it test driving it they say. I am tuned with the Predator with STS turbo.

 

When the CEL blinks, it means that the PCM has detected a misfire bad enough to cause damage to the catalytic converter. It goes by percent misfire.

 

I pulled all my plugs out and the drivers side bank were all black and fouled and the passenger side bank were perfect. Does that mean the O2 in the drivers side bank is bad?

 

The O2 may be bad, or it may be reading some unmetered air entering the exhaust (exhaust leak) and thinking that that bank is running lean and richening it up. I noticed in another post you mentioned having the y-pipe replaced? Maybe the O2 sensor got damaged, or is loose, or there's a leak....