Just rebuilt the engine in my 95 3.4l Camaro. Finally found a scanner that works with OBD 1.5 and fixed all engine codes. Car ran perfect in the driveway but as soon as it was on the road it started stalling whenever you push the clutch in to come to a stop. Only when moving. Replaced IAC and didn't help. Bought the software and cable and flashed the PCM. It ran great for about 5 weeks and then idling at a gas station it stalled and would not stay running without the gas pedal pushed. The next day the car ran fine. A few weeks later it stalled coming up to a red light and again would not stay running without the gas pedal pushed. Next day ran great again.

Any ideas on what is causing this problem?