2000 Nissan Altima Dies at Stops

I have a 2000 Nissan Altima w/72,000 miles. The car starts and when I come to stop sign, red light or slow down in traffic the car dies. All the dashboard lights go on and after the car dies I can immediately start the car again. This also has occured when making a turn and backing into a parking spot. I've had the following changed: rotor, rotor cap and distributor. The throttle body has been cleaned and oil and filter changed too. The battery has been serviced and the connectors to the battery have been cleaned. The car, when hooked up to a diagnostic computer, only once came up with an error code indicating that the distributor needed to be changed, but this didn't cure the problem either. I've been told that my spark plugs are fine and didn't need changing. When I drive the car on the highway it feels like I can't ease up on the accelerator at all at the risk of the car going dead and feels like I need a heavy foot on the accelerator to keep the car at a pace. The car's been to the dealership 3 times and I'm at a loss and frustrated. Help!!