So I had injector 4 throw a code and I was monitoring the injection deviation amounts and it was +5mg. Yesterday I replaced the injector seal and o ring and it nearly fixed it, back down to +0.7mg which is still high but significantly better and way less rough running. You can replace just one injector and it's not too hard of a job, the hardest part is to reach down into the hole and get the old seal out if it doesn't come with the injector. I got a claw reacher tool from O'Reillys and used a bent coat hanger to dig it out for about an hour. You may need to get a slide hammer to pull the injector out if it's really stuck in there. I would try to do the seal first before the injector just to see if you can save the $250 to $300 on the injector
