WD 40 is messy. Use the tip of a Propane torch with the gas turned on but not lit. Move it around the intake manifold to head mating surfaces and the base of the carburetor. When the gas finds a vacuum leak, the engine will speed up and/or smooth out.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!