Jerrye–You still haven’t told us anything about the car’s maintenance, nor have you told us whether the check engine light is lit up. Both of these issues are very germane to the problem that you have presented.
If you purchased this car ~ a year ago, and if it did not come with maintenance records, then–unfortunately–you have to assume that none of the required maintenance has ever been done. When maintenance has been skipped, gas mileage will drop, the engine will soon begin to run roughly and be less likely to start, and–overall–the life of the vehicle will be shortened.
Please refer to your Owner’s Manual and the list provided above by cigroller for what you need to do regarding maintenance.