A simple check with the IAC is to remove it, and have someone cycle the key off and on to see if the pintle at the end of the IAC moves.
If you have over 400K on this engine, you need to start by checking engine compression. Variations in compression between cylinders can cause a misfire and rough idle. Additionally, you need to check the fuel pump pressure to make sure it is within the manufacturer's specs. Since you smell fuel, the pressure regulator could be bad and allowing pressure to get too high.
Tuesday, July 1st, 2014 AT 7:00 PM