vapor Lock??

[thomba02]

I have a 95 blazer 2 door 4x4. i just bought it used a couple months ago from a used chevy car dealer. the day i drove it off the lot, it stalled at the stoplight. i was driving it around the whole day with the a/c on. it was a very hot and humid day. anyways, the dealer saw it stall and took it back to check what was wrong with it, they kept the car for a couple days and then said that it had vapor lock. so i went to pick it up and it was running fine. when school started, i drove it down for a couple hours and then the same thing happened when i arrived on campus. it started right back up but then it would stall again. i took it to the dealer again and they said they did a diagnostic on it and that nothing was wrong. so then it ran fine for a few weeks. one day when i was driving it to work, i turned on the a/c fairly high and it stalled just as i was parking it. the idle went down to the point of almost stalling, then it caught itself and then stalled real fast. at that point, the service engine light came on. i tried a fuel system cleaner and after a day of driving it around, the service engine light turned off.
my question is does anyone know what else might be wrong with it?? any help would be greatly appreciated. thanks.~thom

[GMMerlin]

First thing is to find out what code is stored in the PCM.
When the PCM sees a fault in the emission system it sets a code and turns on the light...it will run the test over and over again until it sees a passing test then turn off the light (in simple terms) but the code will remain in history.
This may be the clue on what is going on..