Hi Cheryl,
How many miles on your XFire ?
What octane fuel do you use?
Should be better than that.
I use Lucas cleaner, upper cylinder lubricant every other fuel fill up, I havery a few of the small injector cleaners containers I fill up from a gallon jug.
do you know if plugs have ever been changed, if so do you know which brand / kind of spark plug?
A induction cleaning helps also.

If gets to the point it is running rich, can mess with o2 sensors, and start plugging up cats.

Any info you can provide will help

TY
Speedy