05 f350 white haze/smoke
 

So I went into the store and was standing at the counter waiting to check out. I saw what looked like a white haze/light smoke coming ftom my exhaust. So when I get outside to check its completely gone. So I get back to the house thinking I've gone crazy and I see its back. But its very intermittent. It jusr comes and goes. Any ideas?:argh: