I first tried to clean the old unit. I then replaced it with a used MAF from a wrecked MB C model (same p/n). There's always a possiblity that it's also defective. I can pull up a graph of the MAF output on the OBDII reader, and I know that both the old and new MAF have about the same readings, and that both vary with load on the engine. I'll try swapping them out again tonight to see if there's any difference. The MAF swap predated the misfire problem by a few months.