Need help

My car has been doing good up until last week. I had over heating problems. If I drive a mile then go in neutral and coast with the car off and cut it back on on the side of the road. Then all of a sudden while cool it started not starting, then it did when I played with the spark plugs wires. The next day I decided to change the spark plugs and wires completely. Also changed one coil pack. Still I could not get it to start without me playing with wires and someone else turning the key. On my way home thirty minutes after the plugs and wires were replaced the car just cuts off. It would not turn over, it would crank, but not turn over. Tried to pop the starter that did not work. Eventually the battery died, I had it charged and put back in then was hit with the whole pass-lock thing. I turn the key and nothing happens it went crank start nothing. So I go and get a new cylinder and key and do the bypass thing. Now it cranks, but will not turn over. I had to put a resistor in the yellow wire to get the lock and key to work too. But finally it cranks. I sprayed starter fluid in the. Throttle body and it just sputters like it is spitting it out. What do I need to do I have been out of work for a whole week? I need help. Code on computer says Egr valve circuit low voltage.