Well first off i just had a skunk 2 intake manifold a b&m fuel pressure regulator and gauge w/ an aem fuel rail all installed and had it adjusted on a dyno. Second i had gains of 11hp from the manifold and tuning(fpr adjustment) But my problem is this, I DROVE 180 MILES ON ONE TANK OF GAS WTF!!!
Did you expect your mileage to go up when you started injecting more fuel? 
Seriously though, I’m guessing once you got all this installed you were pretty anxious to try it out, no? I’d say wait another tank or two before assuming you’re not going to get better than 18mpg or whatever.