This sounds like it may be as simple as cleaning the water or gunk out of the gas tank which is what I always do 1st because it's easy and inexpensive.
Fuel Systems always gets contaminated with carbon buildup, gunk, grime, water and/or bottom junk like rust and this will cause the problems your having!
Fill the tank with High Test, Add some dry gas and a good fuel system cleaner or 2 or 3 and this should dissolve all the gunk and clean the injectors!
Read & follow the cans' instructions carefully.
If this cures the problem never let your gas tank get below 1/4 and especially never run it to empty as this is when the gunk and/or water will enter the system!
jackiaria