I have a very similar setup as yours. I have 65pph injectors with 24psi fpr. I has a very rump, rump rump at idle in park only. It wound up being the VE table not being smoothed out after using the excel spreadsheet, I am using Daves wbo2 excel sheet not the blm one. but from what nuekam just told me is it uses the cells directly around the cell for that rpm/map and if it is closer to the map rpm above, next, below it it will start to use that cell's data. if the 2 are too far off then it will ramp up and down. Also if you have major timing differences between the cells it will dot a very similar thing. At least this is what my issue was.
http://www.gearhead-efi.com/Fuel-Inj...standing/page4
he explains in post #54. I also has a very slight surge at low throttle like .7v tps and that went away also once I fixed the VE table.
Not sure what you are running but I have 26deg at idle in the SA. Hopefully this might help.