2000 C280 Before intermittent start, now car dies while driving

[glenmore]

2000 C280 with about 50m. The problem is an infrequent no-start, with the engine cranking but not catching. At first always after driving for awhile, never a no-start in the morning. Car would drive perfectly normal when it did start. After a no-start and then simply waiting 5-10 minutes, the car would start and drive normal. First thing I tried was a new camshaft position sensor. Car was fine for a week and then a no-start. This time it was the first start of the day. The car then drove normally until I could get a new fuel pump relay. Drove for awhile, then a no-start the next day. Then a whole week with normal operation until today when the car died when accelerating from a stop. This is the first time this has ever happened. Wait 5 minutes, and the car starts and drives normally.

What next to check? Fuel filter? Fuel pump?

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400