92 Hyundai Sonata DOHC idles low then shuts off
 

Got a 92 hyundai Sonata 4 cyclinder mitsubishi DOHC , with the gas to the floor the car starts and can stay on for a bit and then idles low and lower and shuts off. when starting the car with out the pedal to the floor, it starts up and then idles low and shuts off. i can smell gas after both attempts. ive changed the fuel filter, the accelerator, checked the gas cap, change the spark plugs and after i did that i checked them after a few starts with the same problems still. the plugs were full of carbon and black, got dirty quick. is there any suggestions? i need help !