Since you've already pulled out the ring line and injectors, it would be good to see how well matched the injected volumes are, especially if you think you have different injectors mixed together. I don't know what the spec is (maybe +/- 10%?), but it will be hard to get the engine running right if they are so mis-balanced so that the mixture setting for the leanest cylinders makes others rich and fouling.

got the part numbers of the injectors?