Engine cutting out and stalling

[Lou1119]

I recently got my car back after a long hiatus to have it rebuilt. The old trash engine was replaced with a Roush 427SR. Being without the car so long I could not wait to get in on the road. The engine fired right up and I decided to get the tank filled up. I drove the car to the gas station, filled it and started back home. I came to a red light, stopped and started to move in first gear and shifted into second and the engine cut out and stalled. The car restarted easily and I proceeded to move out again with the same result. Third try and the same xxxxing result. At that point I decided to get home in first gear (about 3/4 of a mile).
A few days later I decided to give it another try with the same result but on another pass I was able to get the car to perform well and could shift through the gears. However the same thing happened when I turned around on the way home.
When the car was put back together the fuel pump, fuel filter and fuel lines were replaced with new parts. The only thing that was not replaced with new components was the MSD 6AL box. My tech seems to feel that the box is the culprit. Any thoughts or suggestions?

Thanks,
Lou
My love/hate relationship with the Cobra continues.