Did you clean each individual jet and pilot jet until you could see a nice symmetric shaft of light coming thru each narrow passage? This often requires 'rodding' out the jet using a thin piece of copper strand or strands, stolen from a piece of speaker wire.
The fuel screws (not air - two strokes have air screws, four strokes have fuel) adjust idle mixture from idle to about 1/4 throttle. Rough idle or slow return to idle could be due to their adjustment, but not usually varying idle speed - this is usually due to a vacuum leak somewhere or a sticky mechanical component - butterfly, slider, etc.