One problem related to ignition switch has been reported for the 1999 Ford Expedition. The most recently reported issues are listed below.
Vehicle was parked in school parking lot and the vehicle just started up with no keys in the ignition. The second time this happened the vehicle was parked in a grocery store parking lot. Consumer went in, came out, and the truck was running. Key was in the consumer's pocket. This has happened at least five times. Contacted the dealer. They admitted there was a problem, but couldn't resolve it.