1994 Chevy Camaro Engine keeps stalling at idle

I noticed the engine loping a little, then while taking a turn in a parking garage while breaking, engine at idle, it stalled. It started right back up and stalled again. If I drive with 2 feet an keep the RPM's up it will run, as soon as it idles it stalls. I replaced the fuel filter & cleaned the injectors, I can hear the fuel pump start when I turn the key on. The service engine light does not come on. I took it to a garage to have it hooked to an analyzer to see if any of the sensors were bad, they said no and that it was probably the ECM. I got a rebuilt ECM with my e-prom in it and 4 min after I start the engine it stalls. When its initally started cold it runs and when it starts to stall, if I restart it and keep the RPM's up it will continue to run but not smoothly. I was going to drain some gas out of the tank to see if there are issues with it. Otherwise I'm at a complete loss, I've owned the car since new and have maintained it very wll. HELP !