2009 Honda Odyssey Serve Gas Mileage Loss
 

I know its a common issue with no answer I found yet, but I'm hoping someone has a solution. Have a 2009 Odyssey with 130k on it. In Sept of 2017 (Just under 120k) it went from 18/25 mpg to 15/21 overnight it seemed. I immediately ran fuel cleaners and changes plugs. Over the winter it dropped to 14/19 mpg. In spring I changed Mass air flow sensor, cleaned intake and changed downstream (I think, the one in the front of the engine) O2 sensor.

Dropped to 13.5mpg in the city over the summer. Took it to the dealer, they found nothing but suggested a fuel system cleanse. Went up to 14.5 mpg right after that, but then dropped back to 13.5 next fill up.

Upon changing the rear brakes last month found a glide pin stuck and replaced both rear calipers, rotors and brakes. Front brakes seem fine according to the mechanic who just inspected it. Last night's fill up was 12.8 mpg.

I'm at my witts end. Can't afford a new van at this time, can't keep throwing money at random parts, but its also not economical to be losing 100 miles each tank of gas.

Does anyone have any clue????