We all plan for our installs to go smoothly without problems, yet somehow they never do!
EC36pin27 and 29 is the place to have the pull-up, a pull-down (not usually recommended) would be between EC36pin27 and 26.
And its best done outside the box when experimenting (and probably best to keep it outside the box afterwards. If those of us doing support had our way we'd never see another 'kit' sold).
A Hall sensor is cleaner but has other possible trigger setup problems.
Filtering will not help, it turns on a load of additional trigger settings that I've never seen work.
The fact that it goes away when running is great, it points towards the noise causing the VR sensor chip to false trigger and solves this problem.
But...
What happens when you try a hot start? The pump will be on because the coolant temp is above 30deg.
Which will cost you time and money if you get problems when you're on the rollers.
For a quick and dirty fix, try a 10K, 5K and 1K pull-up and check your cold cranking.