I've got a 98 Club Wagon with a 5.4L V8. Has worked flawlessly since I bought it new in '98...until October 2004. Car has spent most of its life at sea level, but in October I took it above
7000 feet for a week or so. A light on dash came on, saying "Check Engine Soon." I ignored it and everything was fine, until I returned to sea level.This is why I ignored it... Because 5 years ago, I took it above 7000 feet, and the same thing happened. I was alarmed, stayed over an extra day, so I could go to the Ford Agency on a Monday morning. They told me to forget it. So I returned to sea level, that light stayed ON for a month or so, with no symptoms. After a month, the light went out, never to return until our October 2004 incident.
So in October, 2004, upon returning to sea level, I noticed a "sputtering" of the engine, especially noticeable when the engine is cold. I still suspect the engine is "lean," with the fuel mixture being stuck at a setting appropriate for high altitude. I changed the air filter, with no improvement.
So here we are, three months later, and the light is still on. If I get one of those code readers from a parts dealer, will it tell me anything?
Any suggestions, other than the obvious one to take it to a dealer?