Per subject, the cause of the behavior in question has always eluded me... it's one of those things that happens one in every five or six fill-ups at the gas station. Basically, everything is warmed up and running great... no flare etc. not even with a cold start first thing in the morning. Yet, under conditions where I stop to get gas and the engine is off for, say, five minutes or so... I'll pull out on the road normally and get what amounts to a flare on the 2-3 shift.
I've hunted far and wide for information on what would cause this. Given the inconsistent behavior I'm simply stumped. Has anyone here ever run into this before?

