Code solved but MPG trashed?!

I had code P0401 popping a light on my truck for quite some time so I took it to the family mechanic after a month or two of finding no solutions. The code was because of a bad EGR cylanoid and bad EGR modulator.

I told him to go on with it and replace the parts. I've gone almost a thousand miles on the new parts now and no code has popped up so that's solved now.

BUT The reason I pushed to get it solved is because my MPG used to be 18 and then it 14 before replacing the parts.

Today I checked my MPG and I'm done to 12.8 MPG. Does anyone have any clue at all what I should check next?

 

That's pretty poor. I haven't had that code, but was able to up my mpgs by replacing the downstream o2 sensor and charcoal canister. There is a post about it on here. It may have nothing to do with your issue though.

Are you running a 4 or 6 banger?

 

I'm running a 4 banger. I've replaced my O2 a year ago

 

Get a scanner and watch your fuel trims.