I don't know if that will work for David (maybe his/your environment/procedure is different than mine) but I had always done the first wash in citric acid (and a second wash in tap water) with Vandyke and never experienced David's problem when toning in gold/thiourea + I never used running water when processing.
Let me venture a guess: the stain may be a result of how you used the
citric acid "clearing bath". It's important to wash off the excess
emulsion as the first step. When you soak the print in the "clearing
bath" some of the excess silver nitrate could get imbedded in the paper
instead of being washed off, and that would produce stain.
So try skipping the citric acid bath and see if you still get stain. I
never tried using citric acid, but when my students agitate exposed
vandyke in a tray of water instead of rinsing the prints in running
water, they got stain. That's without gold toning, but I suspect the
toning is a separate issue.
Please do report back if you find out.