tuned in. make sure you clean your tb/plenum , iac, and maf. ill make a huge difference.

 

tb/plenum are both brand new with no kind of carbon build up whatsoever. Ive cleaned the iac recently, but it won't hurt

I literally got 145miles to my entire last tank without changing driving habits, I drove 100%city so I usually only get 185 or so but I dropped 3-4mpg to nearly 10mpg just from last tank with basic bolt ons and stock gears.

I replaced the intake manifold immediately before filling up last time so I'm worried I may have done something incorrectly, anyone have any idea on what I could have possibly done wrong to make such a drastic difference in gas mileage?

 

NTK #22060
More Information for NTK 22060

The same sensor, just in a Motorcraft box with a $10 markup: Motorcraft #XC2F-9F472-AA
More Information for MOTORCRAFT dy1039

 

#1. That is a terribly inaccurate method of measuring fuel mileage.

#2. A vacuum leak can decrease mileage due to compensation by the fuel trims.

 

what was so innacurate? The tank before this I drove it to empty, filled up ~14gallons and got 185miles until empty, repeated the process with the same grade gas, gas station and amount of gallons filled and only got 145miles until empty

 

Sorry to hear that, hopefully you get it resolved quick.