You know - I noticed this just the other day: my 190 2.6 gets just slightly rough on less than 1/4 tank. I open the tank and inevitably there's a HUGE vacuum differential. Then I fill it and it's smooth as silk again. So I'M wondering if the pressure buildup has some effect on fuel delivery.
Caveat: I never put this together until I'm fueling or I'd simply try it out and see if the car ran a little smoother. We're talking really slight stumble here - no loss of power or complete die.
[This message has been edited by makakio (edited 08-07-2000).]