first, moving the clip on the needle will do absolutly nothing at w.o.t.
moving the clip (to lower or raise the needle) is only effective from idle to about 3/4 throttle.
after 3/4 throttle, the needle is out of the jet orifice and no longer meters the fuel.
from 3/4 throttle up, the main jet is the only thing that meters the fuel.
normally a bog like what you are describing is caused by the air-fuel ratio being too lean.
this would require a richer main jet.
normally if a carb is too rich, the engine will 4 stroke, not bog or almost quit running.
BUT, it sounds like maybe your float needs to be adjusted.
it sounds like your float bowl may be running out of fuel too soon, and then it gets just enough back in it to make the engine take off again.
too little fuel in the bowl will make it decellerate and as soon as a little miore fuel flows into the bowl it will accelerate, and it will do this over and over.