Thanks Bowtie,
I used Kleenflo (#586) which is approved for GM. I would have used a synthetic if I had known about one (I now know of a part-synthetic from GM part # 12345866)
Up here in Canada you cannot find high quality rebuilds, you have to go to the US. I may go down and get an ACDelco rebuild later if necessary.
Would the 20" Hg pull the air trapped in the rack as well? Or does that have to be worked out? Or, does it sound more like the fluid is self foaming?
ugh. New rack, new pump, new lines, new fluid, and the system is working worse than the original. At least my garage floor is clean now.