Anyone experienced this? I have a 98 ML and after receiving the fuel system upgrade (pump/sending unit, fuel lines, pressure regulator), the fuel gauge is off. With that I mean on a full tank of gas (it reads full on the gauge), the gauge will start dropping to about 7/8 after <10 miles of driving. It will go down to 3/4 after about 20 some miles and now it's sitting on slightly above half with 55 miles driving. I know it's off because when I refuel at half tank (as shown by the gauge), I could only squeeze in about 6 gal. The dealer already replaced the new pump/sending unit once, and it's still doing the same thing. The original pump/sending unit wasn't doing that, it was accurate down to the last few gallons.
Any suggestions.

Thanks
steve