Fuel air ratio too lean?

When I start to drive my car it's like it loses all power, a check engine light starts flashing and I have to pull over, shut my car off, turn it back on and then drive down the road. Sometimes I have to try it a few times before it finally drives down the road. It gets shutters at stop signs or stop lights like the car wants to take off or like the engines trying to cut out like stalling and it doesn't when I slow down into a lower gear. I use the shifter gears on my steering wheel when it starts to shutter really bad to downshift because it seems like it's trying to shift too fast into a higher gear. I've ran the engine codes on it, and they say cylinder four misfire and replace the coil and the spark plug already it says a code for fuel air ratio sensor 2 being too lean and we changed it, but I think it was sensor one that actually got changed. I'm not sure where sensor 2 is located. But when I push on the gas it's like it's not getting enough gas or something I ran fuel injector cleaner through it and cat cleaner through it and it's still acting up I don't know what to do.