well there is lots of water in arizona every night the temp changes and causes moisture . but back to your problem. 5yrs yep your gas is junk. I would not try and run that gas. might try a hillbilly cure get the old gas out ,put in 5gal of new with a couple cans of sea foam . if your real handy disconnect the gas line and get all the old gas out. your plugs might have to be changed? there water logged. or have it toad to a garage and have the fuel system cleaned. at least your in a warm spot to do this.