It doesn't really matter what I say as long as you don't believe me.
What is important is what I experience while driving the car. Last
summer while driving 960 miles along the West Coast, I spent $77
(roughly 32 gallons, I wrote it all down at each stop) on gas.
I checked the EGR, it's working. Perhaps the gas attendants somehow
made the pumps put more gas in the car each time I filled up without me
paying for it and without it showing up on the gas pump readout.
Unless someone would tell me how to test the EVR, as this controls the
movement of the EGR, I would assume it's working and I haven't made
any other modifications to the car. Haven't gotten any SES. And yes,
I changed the oxygen sensor last year.