For mine all the cylinders on one of the banks were misfiring, the dealer replaced that 02 sensor and it seems to be running better.
We shall see, hopefully it's the end of it.
My week old Gladiator is also at the the dealer - less than 200 miles and the P0300 cel...
I'm not sure if it's better or worse knowing from this forum it's not an isolated issue.
Has anyone actually had theirs fixed?