[Apex]

One simple check is to check the torque on the head. Make sure it didn't work loose somehow. That would be an alternative if you don't get any improvement from the oil in the cylinder check. I remember back when I was doing car work that it was having issues with the power delivery on a V8, and one cylinder had low compression. Had spark, fuel, etc. So tried the cheap methods before pulling the head, and a re-torque solved the problem. The gasket was still good, just needed the proper torque.