sn95 v6

Hey my 98 3.8 has a miss fire on 6th cylinder mostly in reverse sometimes idle. Its an automatic but stalls in reverse. Throwing P0300, P0171, P0174. I replaced my O2 sensors thinking it was the problem but wasnt. Any help would be appreciated

all right I got a 97 mustang 3.8 L V6 that cranks and barely sputters when you tap the gas. if I don’t tap the gas it will just crank. It has spark and fuel pump kicks on. spraying some starter fluid in it makes it act like its flooded. The antitheft light comes on for one second then goes off...