Tom-
If one of your plug wires has backed out of the wire end, this can/will cause a miss. Just happened on our 500SEL. Back the wire out of the plug end, (unscrews) put some rubberlube or silicone on the end of the wire and screw it back in until seated. Could be many other things, but this was it on our SEL. Assumes you can identify the missing cylinder. Good luck.
John O.