Can you get ahold of a fuel pressure gauge? Insufficient pressure can also cause problems.

Can't imagine a fuel filter being so clogged that you can't start the car, but it is possible...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car