'03 windstar, trans bucks, lurches

I have a customer with a 2003 windstar which, when warmed, quite frequently wants to buck or lurch forward when in gear, braking at idle. It is such a hard buck, if you are not hard on the brake, the vehicle will lurch forward. Months back, customer had trans code stored for tcc. Replaced tcc switch at that time, but has not solved problem. TCC code however has not returned. This lurching is becoming more frequent and customers wife will no longer drive vehicle. Anyone have thoughts or experience this before. We are not trans repair people, but would still like to help customer. Any ideas will be explorered. Thanks