A co-worker of mine has an "05 unlimited with a 4.0, when he starts in cool or cold weather of first start in the morning, it cranks fine. After his morning drive and the day has warmed up, he has a hard time getting it to fire up; or I should say, excessive cranking. he also says that sometimes while its running and especially when he shuys it off, he hears at noise at the right rear corner of the jeep, i've heard it and it sounds like vaccum valve of some sort fluttering. Any ideas would be helpful.