Missing under load

When you replace the injectors, how do you get the air out of the fuel rails?
Let me back up a bit. The first thing I did was to take this car to the Dodge dealer and have the cam sensor synced. It made no difference. I replaced the plugs, wires, cap and rotor. No help. I replaced the crank sensor and cam sensor. No help. I replaced the injectors and fuel rails. Fuel rails were full of rust. I was sure that would fix it. No help. Today I replaced the MAP sensor and it helped but it isn't consistent. After running it for a few miles, it began to run rough at idle. I reved it up to clear it and it didn't idle back down as it should. This thing is driving me crazy!!