My 98 Catera may be having some kind of fuel leak in the engine bay area. It stinks really bad after driving around and then after parking the car in the garage or anywhere else it's fills the whole place with the fule odor. I think this started after I replaced the valve cover gaskets on both sides. I checked the fuel lines right above the passenger side plug area and didn't see any leak.
Also, on some mornings when I start the car it feels like there's too much fuel / overflow going into the system and it's little sluggish when it starts, but it does start right away. Could it be the fuel injector going bad or malfunctioning causing the bad fuel odor?
I have a 1999 catera and when I had the valve covers replaced about two months agao I had the same issue. I had to take it back to the garage three times before they found that it was one of the fuel lines on the Left side of the engine. it was not put back completely square and since it is a compression fitting was leaking just enough to smelll fuel. After it was fixed no more problems.