If you bring home $350 every 2 weeks, than means you are earning $175 each week, for a total income of $700 every month. If you have to pay $300 each month for the monthly payment on the car, then that leaves you only $400 each month to spend on gas, oil, maintenance for the car, and for any other personal expenses. you might have during the month.
You can't AFFORD a $14,000 car - not even if your mom pays for the insurance. The darn thing would be repossessed by the finance company within 6 months, because you can't afford to make $300/month payments for the next 4 or 5 years, and still have a life of your own.
You don't make enough money to afford to drive a $14,000 car. All of your present monthly income would be going into keeping the car on the road, leaving you nothing to spend on yourself.