i've got a obs '99 tahoe w/ a new motor. it keeps throwing the p1441 "Evaporative Emissions System Flow During Non-Purge". after i reset it, its fine for a while then pops up again in about a week. already checked the gas cap. where should i look.

 

anyone? anyone? (doing my best ben stein impression)

 

Possibly a stuck open purge valve, or a mis-routed vacuum line?