Inconsistent a/f with emu
 

I have had a problem with inconsistent afr for a while. So I thought an O2 clamp might help. I installed an O2 clamp this weekend and gave it a try. See attached log.
http://home.wavecable.com/~laurn/LeanRich.jpg

Note: I'm using a Motorola MPX4250AP MAP sensor, but selecting GReddy. (16.5 Greddy = 2.60 Volts = 6.8 PSI).

For example, the A and B markers are about the same RPM and PSI, but the I/J duty cycle is 70.4 versus 73.8 and the AFR is 12.2 versus 11.3.
Is this something that an O2 clamp can fix if I just keep trying different clamp voltages, (current clamp voltage is 400 mV)? I can't make my I/J map richer to help the area around 757.60 sec, because it is already too rich at 765.60 sec. Any help would be much appreciated.

Hear is the .EM2 file, http://home.wavecable.com/~laurn/30Dec07_03.EM2