Reading other 402 threads in here, that could be it. Hopefully its that simple.
I had a p0403 last week on the van. I'm hoping a blocker plate and efi will take care of it. Cleared it and it hasn't come back. Dont know if it was too much idiling and light foot on the gas pedal. It came on switching trailers around in the back yard.
Thought of you/your van last night. Almost nailed a deer on the way home. He was a big one and it wouldn't have been pretty on my van.