I ran out of fuel and now the car will only idle.

It sounds like you may have a worn out fuel pump. Typically this can cause the car to be able to start but the car will not be able to take any throttle. The best way to conclusively diagnose this issue is to do a fuel pressure test. Running you car really low on fuel can be very hard on the fuel pump because the pump needs the fuel for lubrication and when the tank gets dry, the pump has metals parts that rub against each other with nothing to protect them.