Just to clarify your terminology... if it "turns over", that means the engine is "cranking"... but not necessarily starting. If you had for instance, a dead battery - it wouldn't "turn over" (crank).
Anyway, my guess at this point is a carb problems OR bad gasoline (again), because it sounds like fuel problems. Stupid question (but must be asked): Are you certain the flow direction of the new fuel filter is correct?
I would suggest adding marine grade Stabil (blue, not red) to your gasoline tank AFTER you get everything squared away... and use a different gasoline brand/supplier.
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