Volvo Repair: Intermittent stalliing on 1992 940 GL, car radiator, mass sensor

Question
Over the past yr I have had numerous work done on the car:  radiator replaced, newer used transmission, both seals replaced on that, air mass sensor, & idle motor.  It has just over 205,000 miles on it.  Now it has stalled on me twice as I waited at red lights.  Once it stalled as I was slowing down for the light.  It won't restart immediately but if I wait a few minutes, it will start back up.  My mechanic has had it for over a week but the problem has not shown itself.  The computer reading comes back ok.  I commute quick a distance and the last thing I want to be is stranded.  Any ideas?  I am seriously considering getting rid of it and getting something more reliable and newer.  Thanks for your time.  

Answer
Barbara, I would replace the fuel system relay first.  Have him also check the speed sensor on top of the bell housing on the transmission.  you also may be having a problem with the fuel pump. These are all suggestions since to be sure, I would have to run various tests  on the car.  Roger