I would be willing to bet $ that the plugs aren't going to fix the problem and you'll get the same code back. I fail to see how a standard copper plug would burn any less of the air/fuel mixture which would cause the rich exhaust detected by your P072 code. If the plug was actually bad and not firing, then maybe, but the type shouldn't matter - only for maintenance intervals.
For some reason, one of your oxygen sensors is picking up a reading of a rich exhaust. Did you try cleaning your MAF or checking the 02 sensor itself to see if voltage is still within acceptable parameters???