Help! Leaking gas out of exhaust

I've got a 03 silverado with the 4.3 v6. I have my truck tore apart, I trailored it home from my parents this weekend and when I pulled it off the trailor and it's leaking gass. So I start looking for the leak and on the drivers side where the header collector bolts to the exhaust gas is leaking out, and where my exhaust crosses over there's a small hole and gass is leaking out there. The truck sat for 5 months. At my parents I started it up and let it idle for a long time before i gave it any throttle. It never leaked at all untill i went to pull it off the trailor. It only does it when it's started not with just the key on. Anybody got any help or ideas? Thanks in advance.

You sure its gas and not condensation/water?

Yea I got it all over me last night, I'll still smell like gas after two showers. The weird thing is the truck isn't missing or anything. It sounds like a stuck injector or a stuck valve, but that would make the truck run funny. I'm completely stumped.

check the oil. if its really really thin, your gettin cylinder wash out which can lead to a spun rod bearing. prob a sticking injector or pcm pumping to much gas.

I haven't been running it since it started. Once i get a chance i'm pullin the plugs and seein which cylinder it is.