OK, now that you have the misfire problem solved, did you reset the pcm when you changed the coil? Disconnect the battery cable for at least 10 minutes and then reconnect. I think that the ping you were experiencing was lean condition caused by the oxy sensors setting the fuel trims very lean due to the oxy sensors reading the unburned fuel from the bad coil. Resetting the pcm will set the fuel trims back to "normal" and it will re-learn things faster. Unfortunately that was likely not related to your oil burning issue.
mja, how much oil is the engine using? How many miles before you have to add a quart?