Crazy that I only get this code when I pull my little pop up to the campsite. After i unhook from the trailer the check engine light goes off after about 15 minutes. Not sure why the computer would think that I'm somehow getting more air in the system just from towing. This is on the 5.0 1996 with a 5 speed. I have the last Smog test EVER for this Bronco this month so we will see what happens... the check engine light is off... I will unhook the battery to clear stored codes... and see what happens.