that is a low Rpm to begin with!
once you start modding your car and especially if you remove the airpump you want to raise the idle a bit IMO. I do it to all the cars when I get rid of the airpumps for one it will be richer at idle so if you bring up the speed a bit it will burn a little more fuel and not go tru plugs as quick. I set my idle @1250 rpms and have had no ill effects at all been doing for over 6000 miles on my street port motor I would suggest to you to raise that idle at least to 950-1000 rpms and you should see a big difference in VAC.


-Rikki
also make sure you air bleed screw is set correctly as that will give you a low VAC!