Toyota Repair: Intermitent stalling of 1994 Toyota Celica GT, toyota celica, dashboard lights

Question
QUESTION: I have 1994 5 speed manual transmission Toyota Celica GT with 277K miles. Over the last year the car has been stalling intermittently. The first time it occurred I was stopped at a stop light. While waiting the rpm dials started jumping up and down while idling at the stop light with attempting to stall out. Pressing the accelerator prevented the stalling while sitting at the light. Very shortly after moving forward at the green light the car stalled while shifting gears.  I tried to immediately start the call and it would not. The car sat for about 15 minutes and I was able to start it up and drive it. Between the stalling and restart, my attempts to restart the car within that 15 minutes would start at no response (just the dashboard lights would come on) to a full restart about 15 minutes last where the longer I waited the more response the car would give.  This pattern repeats itself expectantly / intermittently. There is no particular weather or type of traffic that triggers the stalling. The stalling is always preceded by the RPM dial jumping around with the car sputtering then stalling when shifting gears.

I have taken the car to three different repair shops. The distributor and the EGR value were replaced with the problem continuing.  Each location tries to duplicate the problem by letting the car run for hours or taking it on test drives, but of course the problem doesn't show itself when in at the shop.  

Any idea what the problem could be?

ANSWER: Have any of the mechanics that worked on it recently checked for diagnostic trouble codes, if yes do you have any of this information available?

---------- FOLLOW-UP ----------

QUESTION: Hello. No. There are no trouble codes showing up. Per the mechanics, they are not able to find any indications of problems...no codes or signs of worn parts etc. Because the problem is intermittent they aren't able to duplicate the problem during test drives during the 1 or 2!days the car is at the shop either.

Answer
Ok, I'm going to recommend a couple of things based on past experience for this problem on this engine, the coil inside the distributor tends to develop cracks and high voltage leaks, this can be intermittent and temperature dependent, if replacing the coil does not cure the problem replace the entire distributor assembly.