It seems like you have tried doing some of what I would recommend but I'll go through my list. Try exchanging the spark plug with another one that is working properly, it no joy then do the same with a coil, always use a part that has just been working so that you can be sure that it is as good as you think it is. One other thing is a possible vacuum leak possibly at an injector seal, just like a bad plug or whatever it will miss at idle and smooth over with the engine at higher revs. To find that CAREFULLY spray some throttle body cleaner or brake cleaner in the area of the injector or whatever vacuum related thing is attached to the affected cylinder remembering that the stuff burns so don't start an engine fire! If there is a leak the engine speed will go up and the misfire will stop and don't fool yourself when the vapors go in the air intake and you see some results, this test only counts if the area right around the cylinder is sprayed a small amount and you see results. And as I think about it don't rule out the possibility of an injector messing up itself could be the issue. If you have access to a good scan tool like Forscan you can see if the in your case the left bank shows to be lean or rich and does it change when the engine speed is raised.