[Hersbird]

If you smell something weird also check you pvc valve and hose, that smells like a faint burning if knocked off. I'd look at the vacuum lines and egr as well as long as you are poking around.

PS I just read your post better, I see you probably checked the lines if you replaced a hose. If you had the lean condition then a bad O2 sensor can cause that code. My brother's mazda had us stumped on that for awhile. He also threw a MAF sensor at it before we did the O2. Otherwise I would suspect a vacuum leak somewhere.