Not a bad injector specifically. It's a misfire on cylinder 6. That might be caused by the injector, or it could be a spark issue. I'd lean towards a spark problem first as you should be able to check that yourself pretty easily. I'd start by checking plug wires. Check the plug boots and make sure they are okay, and make sure the connection to the coil pack is solid. I'm pretty sure that my plug wires were original when I bought mine a couple of years, and they disintegrated off the coil packs when I replaced the spark plugs.
Since you are only seeing the misfire on cylinder 6, it's more likely the plug or the wire rather than the coil pack since the coil pack should show a problem on cylinders 3 and 6, but the coil pack is a possibility as well. If you want to troubleshoot it, I'd start by checking the spark plug in cylinder 6. If you pull it and it looks bad you can just replace it (Probably should just replace them all at that point), or you can trade it for another plug from a different cylinder, and see if the code follows the plug. If it does, the problem is the plug, if not then keep looking. The next thing I'd do would be to swap the plug wires. You should be able to move the 5-2 wire to 3-6 and and just run the wire over the top of the engine since it won't be long enough to route properly. For a check that won't hurt anything. Swap the 3-6 wire to 5-2, and see if the code moves from cylinder 6 to cylinder 2 which would tell you the wire is bad. If the misfire still stays with cylinder 6, swap the wires back to their correct spots, and try swapping the cylinder 3 coil pack with one of the other two and see if that solves it. If all of that doesn't isolate the problem, only then would I start to look at injectors.
It is possible that it will run fine when you next start it up. Since you said it was fine until towards the end of a longish drive, that could suggest that it is a heat related issue. If that is the case coil packs and plug wires can be fine when cold and have issues at temperature, so you may need to do the trouble shooting with the engine up to temperature.
Picture for reference if you aren't sure which cylinder is which.