Welcome to the forum.....
There is alot of good info stored in here...
I dont have a ppl but i had the same thing happen to me but mine was a 2-fold problem..
You need to check for air leak aroung the cyl. head, by starting it up(after you remove the fan shroud) and spraying some carb cleaner around the head gasket,etc.. (spray everywhere).. If you have a change in rpm's or it dies, you have an air leak there...
Also i think your petcock has died on you.. My issue was the petcock.. they are vaccum fed, so your ppl are close about a line... Replace your petcock and i think you'll be ok, providing you dont have an air leak..
Hope this helps you some... keep us posted...