If it coughs and splutters then dies on acceleration it is quite often the plug.
If it was running good before and it has gone south without you touching the needles it will be something external for sure. Once tuned these motors usually hold their tune very well.

808gx7R - make sure you have re-set the bottom needle to flush from when you screwed it in so far, or you will get lean bog when you lean the top slightly. Start top needle flush, bottom in 3/4 turn from flush. Lean HSN in LITTLE steps until clean running at WOT then lean bottom for good take off.

If that doesn't work you may well have an air leak somewhere, or some dirt in the HSN jet, which will cause all sorts of crazy tuning problems. Pull the needle and blow out the needle seat then tune as above again.