MB says DO NOT use platinum plugs in applications which they didn't come that way.
You will notice that the proper plug for the ML430 Bosch# F8DPER bares no resemplance to the aftermarket numbers used for the 2.6 HR9DPX.
I can't tell you how many running problems I have fixed by removing a set of aftermarket platinum plugs. The platinum plugs used in the long service applications of modern engines are usually specifically engineered to that engine and aren't used in anything else. These plugs are often as high as $15 per plug although the ones for your ML are only MB list $7.50 (MB# 003 159 66 03).
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
[This message has been edited by stevebfl (edited 05-10-2000).]