Hey James, Sounds like you've got a lot of this covered. The stock Fuel screw has: Washer, O ring, Spring. I used the stock items on my extended fuel screw. It worked fine. (Ty Davis fuel screw) Make sure the cap on the Carb Vacuum fitting is TIGHT and not leaking. I put a tiny hose clamp on mine to seal it off. Good idea to go back to stock Fuel Screw. Can't hurt! If still running poorly, try removing Snorkel ... just for laughs. Good luck!