Engine lags and stalls when initially pressing gas-Solution Found?!

If it is folding over, my guess is that it is rising up too high in the bore. You have to bend the link-rod to the arm, to prevent that.
You can check this by spacing up the pump,to it's normally parked position and then dropping the cover back on. Measure from the top of the pump to the cover. Then remove whatever you used for a spacer, and put it back together. Then adjust the linkrod to achieve less than or equal to, that predetermined maximum height. If your engine is set up right as to timing and fueling, then you won't need all of that stroke, so no sense in pushing the limit.
As for lube, I use silicon O-ring lube.
If you have a treadmill in your house, mine came with that silicon lube to put between the track and the support works, where your feet land; samechit.
But silicon lube washes out over time.
I agree on the idea of polishing the bore. But I also think that after you set the plunger-height, your problems should be over.