One problem related to gas recirculation valve (egr valve) has been reported for the 1999 Cadillac Deville. The most recently reported issues are listed below.
First time engine failed while driving on interstate at approx 75 mph. Engine completely shut down while passing semi. All lights on dash came on and total loss of power steering. After serious scrambling to get car off road and bring to safe stop attempt to restart was successful and trip of 600 miles continued w/o incident. Five days later same thing occurred on suburban street in heavy traffic at approx 45 mph causing a lot of consternation by drivers behind me that did not understand why I came to sudden deceleration. Took car to Cadillac dealer and they found no problem. They charged me $112. 50 for engine driveability and performance diagnosis and did replace a defective egr valve which I feel had absolutely no assoc w/ stalling problem. I think after looking at all the other filings of this problem in the NHTSA records, that Cadillac has a real problem and had better get on it before someone gets killed. Dt.