My son's camaro, when you first start, it seems that it runs very rich and idles rough. You can smell fuel in the exhaust. Once it warms up a bit and you rev the engine a couple of times, it idles smooth and no smell.

Someone suggested a MAS? sensor. I dont think it has one.

Could it be the O2 sensor giving a strange reading at first?

 

i think u have both a mas and a maf. could be the idle air control motor needs cleaning. its just below the throttle position sensor on the tb. easier to take the tb off the get to it, unscrew it and clean. if u have just installed a k&n air cleaner the oil from it may have contaminated the maf so u may need to clean it. could very well be the 02 sensors are giving false reading. are u getting any ses light on the dash? try scanning for trouble codes.

 

Mine used to do the same thing, I changed the oil and there is no gas smell now. It still idles rough for a little while at cold start, but honestly I think that just comes with Chevy engines. If you aren't throwin a code then try the above ^^^^

 

Turns out it was the coolant temp sensor. Installed a new one and problem was fixed.