I just did the mod today on the old G4 someone fitted to the PT I was given - and it gave all the symptoms of the one you mentioned last september - sometimes rev, sometimes stall if not throttle not flicked, then occasionally revs its guts out.
With 3 washers under the cam, the cable ball wont engage properly in the cam, with 2 it works alright but the lowest idle I can get is 1500 rpm (on tach).
Going to change the body and see how it goes - but its 40 degrees tomorrow so probably will be inside
