Could be a couple of things. Your fuel pump could be failing or the fuel filter is clogged. If the car is drivable, put a pint of seafoam in a half tank of gas and start driving. : ) You may also consider taking the air filter lid off and hosing down the throttle body with a carb cleaner. If the prob persist, pull the gas supply line off of the fuel dist and test for flow. Pump and filter are both easy to replace and reasonably priced.

__________________
1981 300TD
2005 C55
2004 E500
1999 ML430
1992 400E
1998 C43
2001 SL500
1988 300SEL
1986 190E 16V
1991 190E 2.6