1978 Jaguar XJ6 stalls

I have a 1978 jaguar xj6. When I start the car everything is fine. I put it in drive and head down the road. After the engine warms up and I come to a stop, the engine dies. Upon restart the engine idles properly, but when I shift to drive the engine dies. If I give it a little gas ( constant slight pressure on accelator ) the car starts and when drive is engaged I can drive on down the road until I need to stop, the problem then repeats. Again this does not happen when the engine is cold.