Just replace the plugs, and change your oil. The plugs are notorious for failure. If you want to get more involved in it then get you an infrared heat gun and shoot the exhaust manifold right at the cylinders. Guarantee you got a dead cylinder, swap the plugs around and I bet your dead cylinder changes. You’re not running lean, you’re loading the cylinder with unburnt fuel and it’s igniting in the exhaust causing your glowing condition. Also the unburnt fuel is making its way by the rings into the crankcase and I bet you have milky oil from fuel dilution. Swap the plugs and change the oil. When you put the plugs in just barely snug them, I don’t remember the torque spec on them but it is not very much to keep from cracking the ceramic. I’ve been down this road a time or two, thought I had an injector issue and the dealer told me they can’t flow test them and their diag consisted of throwing parts at it. They couldn’t even plug into the ECU to diagnose it so I did it myself and saved a lot of money in parts and labor. I started with swapping the coil packs over and my dead cylinder remained the same until I swapped the plugs around, when I did that the dead cylinder changed. These machines have some fragile plugs in them and have been updated at least once that I know of. Get the latest part number for the plugs. From an idle you can’t hear that it’s running on one cylinder but if you drive it you should feel it and notice the exhaust getting extremely hot and glowing red.
