Lately it seems that whenever there's high humidity with rain/snow the truck doesn't want to start. The temperature itself doesn't seem to be the issue; as long as the air is dry the truck starts fine. The truck cranks fine, but doesn't catch. Occassionally, if I keep cranking, the truck *will* start, but run rough for the first minute or so. Before I start randomly replacing ignition parts I'd like some sort of idea where to look first. The plugs and wires are a couple of years old, but the cap and rotor are new. There also seems to be a strong smell of gas when this happens, almost as if the engine were flooded, but it's EFI, so that's not possible, is it?
Thanks for any suggestions.