I get around 24 MPG where the car is set at right now. How bad is yours? I think your setting are right. Its not going excessively rich so I'm thinking that's not causing it. I have found that these motors m103 and early m104 like it a bit rich at idle and little leaner on the top end. Mine will smack 6500 before I realize it. Sometimes she's a bit fussy and 2500 to 4000 will be a bit soft.