1999 taurus dying problem?? help?

hey guys got a 1999 taurus 3.0 motor,149k miles,runs great everything worx, but every once in awhile it will just die,i replaced the egr valve and the electric egr thing sorry dont know what it is called both part numbers are egr 3001 and egr 1328 anyway still does it,took it to the shop this am they let it get hot drove it for 35 miles,put it on the machine and they couldnt find anything wrong with it, any ideas or where to look next,preferably without the process of elimination cause its getting to expensive lol thnx in advance for any and all help. bb