I am getting cylinder 1 misfires on my ML320 - no other codes on OBDII. I exchange coil and wires on cylinders 1 and 2 and get misfires on cylinder 2. Typically, it runs ok if I just reset the DTC's but recurs within a week or two.

Could this be anything other than the #1 coil or wires?

This coil and wires were replaced at a dealer a couple of months back at a cost of $650 (towing ...). I would hope it wouldn't be failing already.