My 340 getting 6 mpg

well, there's part of the problem.
Miles are miles guys. My speedo not working is 100% irrelevant

You dont have to be a mathematician to know that I drove 81 miles combined. 62 yesterday and 19 today and my brand new fuel tank that is 18 gallons, (which i filled up completely full before my day out yesterday) my brand new fuel guage is saying my tank needs a refill speedo or not now im getting 5 miles to the gallon

Did i get on it a couple times. Well duh ! But i dont believe 1 or 2 pulls to 4500rpm can really affect your mpg that drastically

But we did suceed in getting the motor to make more power