A quick question after rereading some of the posts here. How did the initial mechanic determine that the AFM lifters were fine? Personally, given all the issues that folks have had with AFM lifters going bad, I would have considered replacing the lifters when he had the head off to check them, but that’s just me. I mean, he was already there. That being said, I would check everything involved with #4. Start from square one. Swap plugs with #2 and see if it moves. Swap wires with #2, swap coils, etc. I still think there is value in checking you coil harness as well. There was a guy on here a while back with similar issues, but on the other side of the motor. He ran in circles doing everything except check the harness and that’s what it ended up being. When trouble shooting, you have to rule out stuff, not just dismiss stuff. For work and on my vehicles, I’ve had too many brand new parts that were DOA and too many seemingly unlikely things end up being the cause to not look at everything.