A hard uphill pull with low intake vacuum and a fair amount of blowby will turn that air cleaner hose into a road draft tube. That's what usually causes crankcase vapors to end up in the air cleaner. It's one of the early warning signs of worn piston rings.
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!