Thank you very much rikki for your help. The Fiat tester helped a lot to reduce my worries.
the current problem is misfire, and misfire is usually easy to be fixed if not sensor problem.
it seems to be providing excess fuel supply.
At first, as Rikki suggests, it may be the water temp sensor detecting cold temp even when engine is hot.
But just now when I re-park my coupe, the engine was cold, the fuel was still in excess, very bad exhaust smell.
I am suspecting something else.
