i have a 91 gt, with a stock motor. when u firt start the car it runs great, after about 15 mins or so a check engine light comes on, and it will continue to run fine until im sitting in bumper to bumper traffic and then the car suddenly starts to run like crap and then stalls. and if i try to start it again it will eventually start but immediately stalls after a few seconds. if the car sits for about a half hour i can start it and it will run fine, i guess because the code clears itself after a while. i havent done anything to try ro fix it yet. any info about the problem would be greatly appreciated.