I traced the problem of my slipping under acceleration. While initially I think it was due to the fact that I didn't have the lifter pins turned out sufficiently I later realized it was due to not enough slack in the cable.
For some reason and I don't know why exactly, I adjusted a very small amount of slack into the cable but after riding it seems like the slack would get taken up (I might have been imagining things), but I noticed it happening, under hard acceleration it would slip.
So I reached down and turned the adjuster on the lever in some to give it some more slack on one of the longer straighter sections, then got back on it with some determination
No more slippage under throttle.......weird, but fixed now