Car Idles Rough & Violent Shake?

The fact that your idle speed is being controlled is an indication that your IAC is trying to compensate for another problem. The EGR valve could absolutely be causing you some grief because it creates a vacuum leak and can lead the computer to log some trouble codes in other circuits. Pull it off and check for carbon possibly holding the valve open. A mechanic can attach a good scan tool to vehicle and check a bunch of parameters while the engine is running and could be able to run down your true problem. The gas smell could also be due to a misfire caused by a defective EGR valve.