Volvo Repair: 1993 - 850 Stalling, flash flash flash, fuel pump relay

Question
I have read some of the other post that were asking this same question.  My 850 is stalling more than ever... the temp is up to high 90's and I wonder if that has anything to do with it. My car stalls when idling and when driving.  There is a drop on the RPMs and then dead.  I have to wait 3-5 min to restart and then we're off again.  I have read the answers such as Wires, fuel pump relay and a few others.  I changed the fuel pump and plugs already.

This is so ramdom and sometimes I go for 2-3 weeks without a problem.  Have you discovered what the cause of this frustrating problem could be.  I cannot afford to have a mechanic repeatedly changing/trying/testing out different things to end up with this problem.  Please Help Me.. I cannot run my ac because that seems to cause more stalls... and it's HOT here in Memphis.

Answer
there are many things that can cause this.first I would try to check for codes. below is how to do so.

behind the passengers side head light are 2 small black boxes,1 marked A ,and 1 marked B.on box A there is a small wire insert the wire into the hole marked 2 then turn the ignition key to position 2 but not started.then on the box narked A push the small button for 1 second then release it.the small red light will flash a code back as a 3 digit number.there is a short pause between flashes for a single digit and long pause between the different numbers.example:
a 121 would look like this flash.....flash..flash....flash
write down each code,then after the first code repeats its self then press the button for 5 seconds the light will light when pressing button then go out when released,then the light will light steady again when it does press button fo 5 seconds again,this should have reset the check engine light.let me know the codes. i will tell what they refer to.
         Rege