What's that noise? Hissing and misfiring

[gabluebug]

My 1998 Blue Bug starting misfiring under a load last week. She's popping a p0303 code - cyl 3 misfire. Strange thing too - when I shut her down, she hisses for about 3 - 5 seconds from the drivers side of the engine. Also, I sometimes smell gas immediately after she's parked. I've tried to isolate the hiss and can't find it. She had popped a P0440 code a week or so ago, but she does that sometimes just for fun. Anyone have any ideas before I go dismantling things? Just a bad plug? Maybe fuel injector issue? You guys always have the answer! Can you help me out here this time?

[D2Beetle]

Just off the top of my head...

1) Check all rubber gas hoses for leaks
2) Plugs and Wires
3) Coil
4) All Fuel injectors

[gabluebug]

Well, it was simply a bad plug. I changed out all the plugs this morning and she's running like a scalded dog again. Went to the local Quik Lube and had them clear the codes and all is well. As for the hissing noise, maybe it's normal and I just never noticed. I couldn't find anything amiss - checked all hoses everywhere - and right this instant it doesn't appear to affect anything. So, we'll keep rolling on and enjoying the beautiful Georgia day! Thanks for the help.