Sounds like your choke cable may have slipped. Had a 97 GTS that had a loose screw on the choke cable and choke would not open all the way. Started great but died right away, even when I pushed and pulled the choke. Remove the air box and use a mirror to see if the choke plate / plates are operating fully with the choke handle. If you still have to remove the carbs, try a torx socket bit in the stripped allen head. Sometimes the open edge of the torx bit will grip enough to at least break the bolt loose. This has work quite a few times for me on the SS Metric Allen bolts. For your restricted pisser, unhook your small hose from the exhaust pipe and put air to the blocked pisser. Noticed in your video that you have a garden hose to the exhaust side but it was only trickling out of the open pisser, I suspect you have blockage in your post engine cooling lines. If possible, remove the carb side hose and take each hose and put air to them in both directions. I doubt if your blockage is in your head or block. Good luck
