Put your stock injectors back in until you get it running, swapping injectors takes about an hour if you have a second set of hands with you so isn't a big deal to do if that turns out to be the issue.
The fewer variables the better IMO when setting up a new engine/heads/cam especially if you can't tune for the injectors.
You've got to remember most 42lb injectors are rated at only 43.5psi effectively making them 48lb injectors by GM's fuel pressure std of 58psi. Since your stock injectors are likely either 24 or 28lb depending on what year vehicle you have your pcm is trying to trim 50% of your fuel, the stock pcm can only trim 25% so 25% of your extra fuel is not being trimmed out. if your commanding 11:1 afr at startup idle multiply that by 75% and thats probably the rough afr your engine is seeing. Bad idea.
Stock tune+48lb injectors
