I had a similar problem with the solution being the fuel pump.
There are two tests to look at fuel pump fitness: Fuel pressure and fuel volume. Could be your pump is delivering adaquate pressure but cannot keep up with demand.
1985 500SEL (260,000 miles) SOLD!
1974 280 SOLD!
1994 Volvo 850 Turbo Wagon (Yuppie Ice Sled)
"I know I have a Benz and they know it too." If you start bragging about it or shoving in people's face, you then become a Wally; especially to the girls.