Owner needs help.

Hi whunter

Bad MPG 1998 E320 150,000 miles.

I spoke with you a few days back regarding my 98 E320’s poor gas mileage.
I had the car checked for leaks but they did not find any which is good news.
The fuel trims were also checked and they were all within specs.
The last time that I filled up the tank I had added the Chevron Techron fuel system cleaner and today the low fuel level light came on at 360 miles.
I do feel that the exhaust vapors are a bit rich but only sometimes, other times you only feel like clean warm air is pumping out.
Can worn plugs or any bad vacuum lines cause this?

· The fuel filter was replaced @ 143,000m Sep 2009

· The Plugs were replaced @ 93,500m Apr 2005

· The cats were recently cut off and inspected.

· There are no codes on the computer.