4r100 trans torque converter wont unlock?

i have a 2002 ford f250 4x4 5.4l gas v8 with the 4r100, when i beat on it in the mud or sit at a stop light for more than a minute the converter lockup and kills the motor. i have read that it could be the solenoid packs or the pump? i really dont have money for both so if someone might know more and thinks they know what it could be i would appreciate it.