In spells in my own locale,over the years, I clearly remember throttle problems related to entire areas with bad fuel deliveries.
I recently read a blog about jeeps complaints about throttles sticking as well...not just appearing because toyotas did, it has had a random problem for some time as well.
My own car spewed diesel without definition.
On a sranger note, fuel is volatile, what is to say micronic rumblings on our suspended cars isn't making a distillery with haiti cracking at the world and yellowstone with many micro shakes...
in cold weather I could guess a diesel like substance getting left behind, and in the warmer climates, crazy thottles to light fuels..lack of fuel cells makes this all too possible. Hell, from 5 below to 32 above the same 5 gallons in my tank is 1/8th reading to over half a tank on the guage... gas does something in the closed unbaffled containers.
I hardly think that I am overthinking this subject. I have twenty years in maine.
Nothing is crazy in the automobile subject.