Recently I've noticed that my 2000 E320 wagon has taken a few extra cranks before it starts. Then the other day when it was about ~85 F, after driving for 15 minutes, stopping for 30 minutes, and trying to start it would crank but not start. It took about ten full cranking cycles until it finally started.

No other problems once it has started, does not hesitate, started again once home.

I've read many of the threads related to this issue and have narrowed it down to:

Fuel Filter?
Fuel Pump?
Mass Airflow Sensor?
Bad key?

Car has 100k and service is up to date except I need to put in fresh plugs.

Even though there were no faults displayed on the center console, maybe the ODBII could hold some clues?

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2004 E320 4matic
2000 E320 wagon
-- in the past---
1992 190E 2.3 5-speed! (European Delivery Baby)
2000 ML320
1978 240D - 340k mi