99 Taurus tranny lockup at idle

I have a 99 Taurus with Duratech 24dohv v6. When putting it in gear forward or reverse it seems like the trans is locked up and kills the engine if im pushing the brake. If i let off the brake before it dies it will go and shift fine until i need to stop. It comes and goes sometimes it works fine. Poss. converter problem ? or are there sensors causing converter to lock up?

there is a converter solonoid, unfortunately its a bitch to get at.

Thanks drdisque......So far it hasnt done it again.Been wanting to trade it off for something bigger anyway . May be the time to do it. Thanks again.