[cleanspeed1]

I know you have made mention of the EGR system, did you get a code that says that the EGR function has been compromised in some way? Is the "check engine" light on? How many miles do you have on the vehicle? Some things, like the O2 sensors even if they don't trip the CEL will lose their sensitivity after a lot of miles and the mpg starts to suffer. Stop and go driving does not help the situation any.