My 1999 ML430 (about 98,000 miles) just recently started acting up. About two months ago, I experienced a "longer than normal" crank/start time (in the garage) ONE time. Everything normal since then until last week when engine died at a stop light. Immediately restarted. Today, drove it about 2 miles. Came back to car 1 minute later and it would not start...cranks strong but won't start. Look for roadside service card and try to start one more time before calling for a tow. Engine starts. Make a few more stops, turning off engine and restarting without incident. Stop at the bank drive up window, leaving car running but in park. Put car into drive and engine dies. Doesn't restart the first time (good thing the bank is closed today). Wait one minute, car starts and head home to get it into the garage.

I have the new fuel filter arrangement (done about 30K miles ago). The MAF is new about 20K ago (and eliminated check engine fault light). I'm guessing it's the CPS (or hoping so because this is a repair I can do myself). Can a defective CPS cause a running engine to quit? Or does the CPS only "do its job" during starting conditions? Is the CPS a device that fails/degrades slowly or instantaneously? Thanks for any and all inputs.

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Jim