Stihl FS80 avr carb issue

[ghost1]

Have read some of the posts regarding the old style carb on this unit and have attempted some of the fixes without any results. Engine will start but will only reach full rpm with high needle adjusted all the way in, and then, just barely. When air filter assembly is attached, it wont run at all. Have rebuilt carb, tried adjusting fuel metering mechanism, checked muffler to make sure passage is clear, and sealed the overflow nipple coming from carb. Any suggestions would greatly appreciated.