taurus stumble?

Evening people!37 years in the repair of autos, and I'm stumped! I'm trying to get a 2002 taurus, 3.0 to "act up" so I maybe can fix it! The customer says the engine will start to stumble, like it's gonna cut off, and then the security light comes on! He says it's intermittent, and I've driven it 40 miles with no problem! He also stated that it has never cut off; it just felt like it was! I've checked obd, naturally "nothing"; I've checked all components on the engine ie: wiring, wiggle test, vacuum leaks, my machine shows all parameters are safe; fuel, ignition,air flow-in and out, sensors are within tolerences! I'm Stumped!!! Has anyone seen this problem?, and if so, what is the cure??? Thank you all, Tommy

prolly a bad PATS key. if they have more than one key, try test driving with every key in the ignition. aftermarket keys have been known to give problems... at least on the mazda/ford trucks they will. ill have to assume that it could happen on a taurus. if you can isolate it to a certain key, than youll have to replace it and get it programmed, probably by a dealer

PATS=Passive Anti-Theft System