[Lefty]

Yarddog,
You say that turning the Fuel Ratio mixture screw in either direction DOES NOTHING. What that tells is that either the PILOT JET and or ITS PASSAGE are clogged. You are basically keeping it going by raising the IDLE using the IDLE SPEED screw.

So take the carb off and make sure you can see daylight through the PILOT JET then Stick the Carb Cleaner in the PILOT JET hole and SPRAY the SPRAY SHOULD COME out by the BUTTERFLY. You can hold the butterfly open and you will see about 4 tiny PILOT JET FUEL OUTLETS spray must come out of those holes. If it doesn't you can take tiny wire or tiny needle and poke the holes a little and spray and poke until spray does come out.

The RPMS must CHANGE with turning the fuel ratio in either direction at some point turning it CLOCKWISE it may kill your motor and turning to far counterclockwise will make it start sputtering or dieing from to much fuel.

You want to get the highest IDLE(RPMS) when adjusting the Fuel Ratio Mixture. And like I said if turning it either direction does nothing it is clogged.
Lefty