My '07 Nitro (4.0, auto, 2wd) occasionally has trouble starting (cranks for 4-5 seconds before firing) when the ambient temp is above 95 degress, which is often because I live in Vegas. It's happened right after being driven and also after sitting out all night. I ran my code-checker and it didn't pull anything. It acts like its vapor locked, cranking until fuel gets to the rail then starts and runs fine. Its always fired right up and hasn't stranded me yet, but I'm not about waiting for it to die in the middle of nowhere. Anybody have any ideas?