Ah so 370/740 = .5, makes sense.
Can you adjust that number with rpm? Something that you could set it at 68% for idle rpm and 50% at redline with it being linear in between?
I still think it might be the pump if it's not just a power fc issue. You do have an upgraded pump of some sort, right? And is it relatively new?
Also, as was said, it could just be different latency. Try setting the injector correction to 50% as expected and then adjusting the latency until you get a good idle and see how it runs then.
Here are some times for you to give you an idea of a normal range:
Power FC Injector settings - Get your car drivable to get it to your tuner - Hardtuned.net
Also, is your battery/alternator good? I ask because injector latency changes with voltage.