Don't listen to bill67 on the Snake oil cure all of SeaFoam, Do the right thing and pull the carb and clean it properly and replace any hoses that have become brittle or are starting to deteriorate. Your clunk pickup also sometimes it's a stone type filter for the clunk pickup may also need to be changed as well in the fuel tank.
bill67 thinks seafoam and klotz oil will magically cure anything when it comes to engines, he even claims that if you use them you will never have to change your oil.
If something like that had truly been invented all other brands would now be non-existent and engines would last forever, which we all know is not true.
If after cleaning your carb and adjusting it properly plus the air filter cleaning if it's foam or replacing if it's pleated paper, it still doesn't run properly then your issue could be a little more involved meaning the reed valve has gotten stiff or cracked, which could cause the same symptoms. I had this happen on a weed eater type engine once that I had converted to glow fuel for use on large scale R/C airplanes. It's a fairly simple fix but you gotta tear down the engine to replace the reed valve.
R.F.