I have a 2001 TT convertible 225 HP with check engine code P1136(too rich/lean) I replaced one air hose that leaked but ever so often I hear a air leak when starting engine but goes away. I did smoke test and don’t see any leaks and still have check engine code P1136. Is there something that would make leak and go away when I try to find it? Is there some part that could be causing that before replacing all kind of stuff that I don’t need to? Thanks for any help