I have been doing alot of research and diagnosing on my truck for the 337 code. I have found the DPFE Sensor is putting out almost 5v constant on the signal wire and of course 5v on the bottom wire. I am curious since this is bad could this cause bad MPG? On all highway driving I'm only getting 20MPG. I would thing that 2.3L 5 Speed Manual would do a little better than that on the highway. Let me know what you think.

Thanks in advance!

 

Bump.

 

Yes, improper EGR function will effect MPG.
No EGR function with reduce MPG.

Also on any engine coolant temp effects MPG, running too cool, an issue with 4cyl, will cause a decrease in MPG, it is like running with the Choke on with a carb engine.
Gasoline engines need to run with coolant between 200-220degF for best MPG and lubrication, all oil is rated at 212degF, so 30w oil is 30w at 212degF
On most Fords the center of the temp gauge is 220degF

Fords use a 192 or 195degF thermostat, to get up to 200deg ASAP, but in cold weather the 4cyl just can't generate the heat, people often put cardboard or ?? in front of the radiator in cold weather to lessen the airflow into engine compartment, this can keep engine temp higher, especially on the highway.