2003 Ford Focus DTC PO204

I posted something earlier so I will start again. This car has had a problem for a couple of years, I have been putting it off. At first it had a DTC PO302 and P2274, so I fixed the misfire code I think I put plugs in it or something, and it just had the P2274, and since it wasn't stalling or dying I have been putting it off, but now I tried re-setting the computer and now they can tell so it was a fail and now it is moving permits, and this car all it does is hick-up once in a while when idling only, but I took off the fuel rail the other day and cleaned the injectors out with a jumper wire hooked up to a little 9 volt battery, and when I put it back on it has a code PO204, and I tried swapping injector 4 to 2 and 2 to 4 thinking maybe it is the injector but it is still the same and I tested to see if it had 12 volts and it did and tested the signal and the connector looks good and I did fool around with any grounds, does anyone know where I should go from here, it is clear that something that happened taking the fuel rail off and on because I never seen this code till now. Can someone please help.