Started my jeep after work today, and all was well until it started coming off of fast idle (I'm assuming this is when it starts going into closed loop). It started missing and generally running like crap. It started gradually comign off fast idle ( mine always takes its time doing this, don't know if thats normal) and once it reached regular idle speed, it smoothed out and ran fine the rest of the day. Checked codes with my Aerotech gauge when i got home, and it gave me a PO455 which is EVAP Purge System Large Leak. Anyone ever get this one? Any ideas? I installed a skidrow evap skid last week, but it never gave me any trouble till today, and I looked under it this evening, and I didn't see any damaged hoses or cracks in the canister. Don't even smell any gas to tell you the truth. Could it be a bad gas cap? I'd think I'd get codes alot more often if I had an external leak though. Could the valve have just gotten stuck open? I'm thinking maybe thats what happened since it affected the way it ran too, but I think there is a code for that as well. I don't know. I'm gonna wait and see if it does it again before I call the dealer I think. I gotta take it in at 6,000miles to have them recheck my lifter tick, might just have them check that code then.