I just put in the 550cc injectors and the car is running like complete crap. I am using the SAFC II and pocketlogger to adjust them and it doesn't seem to be doing anything. It is like the logger don't want to make up it's mind. One minute it will be extremely rich, the next it will be extremely lean. No in between. What's the deal? Also the car hardly idles, sometimes if I don't give it gas it will die. My buddy just put 550's in his GST and his runs fine without even tunning them. Should my car run fine too? You think one could not be seated properly? I'm lost, thanks.

double check the connections on the safc and make sure your bov isnt venting into the atmosphere.(althought it really shouldnt effect anything at idle.)

Make sure the injectors are seated flush. Also, were the rubber spacers that came out of the intake mani in good condition? Sometimes they can get brittle and cause problems like intake leaks. Also since you ahve a logger, what are your short term fuel trims? Its natural for your 02s to cycle at idle but your fuel trims will let you know whether you are rich/lean.

Well I got a CEL P0300 and it says that is a random missfire. Any idea's?

check the gap on your plugs. Maybe you're not getting a complete burn.

I hope you changed your fuel filter at the same time.... that is a must when changing injectors