Are you referring to the Torque Convertor Solenoid in the transmission, which can malfunction and cause the vehicle to stall out when slowing down after travelling at speeds above 35mph?

If so, how mechanical is your husband?  Replacing this will require at least two hours, the removal of the side cover of the transmission housing (about 13 bolts) and some work inside the transmission running a wiring harness. It's not a HARD job, but you need to know what you are doing when you are inside the trans.