On the original question have you guys put a noid light on the suspected bank to see if it's toggling the injectors properly?

Shooting at the wind here but maybe it's a harness connection issue on one bank with those crappy "salt&pepper shaker" connectors. I always use a pick to spread the male ends out a little by pushing on the center of the male pins, add some dielectric grease and reconnect, they can be a bugger to get back together though after you spread the male pins .