Windstar 1997 stalls when cold

have a 1997 Ford Windstar that stalls during the morning when I first start up for 5-10 minutes or so or stalls when I let it set for a while. It has a 3.8 L engine. I just had the engine rebuilt and it didn't do this before the rebuild. If I have the radio on there is a click on the radio when it stalls. Sometimes when it stalls, the radio, after a delay, goes out for a 20-60 seconds and then comes back on. The rebuild was initiated when I had a leaky head gasket on the No. 1 cylinder. Now runs really smooth except when the problem acts up. I feel there is some power loss though at times, but am not sure about that.