Are you sure it's necessary? I already toned down stinking cloud from nauseated to sickened, reduced fog cloud from 10 min/level to 1 minute, and blindness/deafness from permanent to 1 hour. I think the 1d4+1 rounds for lingering stink sounds good, though.
Oh, sorry. I registered that you'd downgraded it from the default for stinking cloud. It's fine as-is.