87' Firebird 2.8 V6 Starting Troubles

My Firebird has trouble starting at first(have to crank it a few times). After I drive it around it starts up no problem on the first try while it is still warm. After it is parked for an hour or so it has trouble starting again. Any suggestions on what the problem may be? Some friends have suggested that I replace the cold start valve.

Short of fouled spark plugs, yeah, I'd give the fuel system a once over after replacing the filter.