Go get the BerryMans. And dump it in there. Run it and see how much that helps. Next we can pull the caps off the carbs and see what diaphragms look like. You seem to be familiar with the basics so when you have the side covers off you will see the carbs with 4 screws holding the cap on. Do these have a funny looking screw in one corner?If not somebody has been in there. Small vice grips can get the strange one out. Carefull pulling the caps so you don't loose anything and can put it back right. You will find the diaphragms and slides. Make sure slides are working right. In and out with NO rough spots. Hold the diaphragms up to a light in dark room and see how many holes you can see. Now I'm tired. That was a lot of work. Let me know after nap[ time is over.......