Hello All,

I am the original owner of an ML320 with 73K miles on it. Reciently when the engine reaches 4000 rpm, it stumbles and pulses, like it is fuel starved. CEL codes are P0455, P0460 and P0170. I have an appointment with the dealer for thursday but would like to know as much as possibe about the problem before then. The fuel filter has never been changed, but it has new spark plugs and runs great below 4000rpm. The stumbling problem occurs in all gears and also when revving the engine in neutral. I appreciate any ideas you may have.

Pat O'Rourke