was it a bog (boooooooorrahhh) or a spudder? if it was a bog, you may need a richer pilot,, and a leaner pilot if its a spudder (too rich). Since you said it runs better with airlid off, maybe its too rich (spudder).
Maybe you can check your air flow system to see if anything is (like old foam) is inside your airboot, or maybe there is a dirt dobber nest in your silencer or maybe some blown packing. Also clean out your carb including the choke. let us know what you find out..