Originally Posted by ukprometheus
the original plan was to run the engine at 100:1 but thought to help wear on the engine run it at 75:1
maybe that was not such a good idea
So let's look at this again: He's "over-oiling" the fuel mix and he's stalling at low revs.
I'd clean the plugs (or maybe fit new ones if they're old) and try the correct mix, see how it goes. If that fails, plan B beckons!