From my experience, This was due to a clogged cat.
I hesitated and troubleshot everything else, and a new cat solved that problem.
However - I also had a injector short - where my injector had a open ground.
Controlled by ground - the injector was stuck on - spewing fuel, this is something to look out for.
But the description to me screamed "clogged CAT", so I wanted to post.