I've tried both platinum and copper cores in the 103 and couldn't tell the difference.

Shaking and rattling up a long hill...

Is your fuel filter reasonably new?
Are you running Premium?

I'd throw in a can of fuel injector cleaner and a tank of gas from a reputable supplier.

__________________
D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.