When it's your first one man, they never last as long because you make the simple mistakes you haven't learned about yet. It's not a bad thing, it's just part of the learning process.

And 1.5 gallons for a first timer on a pro .15 is not THAT bad either. Those motors don't last long for anyone. If I were you, I would look into an OS .12 CVRX and you will find a whole new world out there lol. It will tune so easily and be so reliable all you will have to do it put gas in it and drive. You will get a lot more enjoyment out of the hobby with something like that in there.