1990 Pontiac 6000 rough idle

cleant your throttle plate with choke cleaner on both sides as that canreally effect your idle. it may be hard to start but make sure your duct isreconnected prior to starting. If that doesn' help it there is a what they call a purge valve on yoru cannister ,for fuel. There may be a vacuum line running to it and it may be on the pasenger side of the car at the front. It is red. It is supposed to open at 30 mph to burn off excess fuel in the cannister, but somtimes sticks open an dcauses idle problems.